Protein (nutrient)

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Protein_(nutrient) 

Amino acids are the building blocks of protein.

 

Amino acids are necessary nutrients. Present in every cell, they are also precursors to nucleic acids, co-enzymes, hormones, immune response, repair and other molecules essential for life.

Proteins are essential nutrients for the human body. They are one of the building blocks of body tissue and can also serve as a fuel source. As a fuel, proteins provide as much energy density as carbohydrates: 4 kcal (17 kJ) per gram; in contrast, lipids provide 9 kcal (37 kJ) per gram. The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition.

Proteins are polymer chains made of amino acids linked together by peptide bonds. During human digestion, proteins are broken down in the stomach to smaller polypeptide chains via hydrochloric acid and protease actions. This is crucial for the absorption of the essential amino acids that cannot be biosynthesized by the body.

There are nine essential amino acids which humans must obtain from their diet in order to prevent protein–energy malnutrition and resulting death. They are phenylalanine, valine, threonine, tryptophan, methionine, leucine, isoleucine, lysine, and histidine. There has been debate as to whether there are 8 or 9 essential amino acids. The consensus seems to lean towards 9 since histidine is not synthesized in adults. There are five amino acids which humans are able to synthesize in the body. These five are alanine, aspartic acid, asparagine, glutamic acid and serine. There are six conditionally essential amino acids whose synthesis can be limited under special pathophysiological conditions, such as prematurity in the infant or individuals in severe catabolic distress. These six are arginine, cysteine, glycine, glutamine, proline and tyrosine. Dietary sources of protein include meats, dairy products, fish, eggs, grains, legumes, nuts and edible insects.

Protein functions in human body

Protein is a nutrient needed by the human body for growth and maintenance. Aside from water, proteins are the most abundant kind of molecules in the body. Protein can be found in all cells of the body and is the major structural component of all cells in the body, especially muscle. This also includes body organs, hair and skin. Proteins are also used in membranes, such as glycoproteins. When broken down into amino acids, they are used as precursors to nucleic acid, co-enzymes, hormones, immune response, cellular repair, and other molecules essential for life. Additionally, protein is needed to form blood cells.

Sources

Some sources of animal-based protein

 

Nutritional value and environmental impact of animal products, compared to agriculture overall

Categories	Contribution of farmed animal product [%]
Calories	18
Proteins	37
Land use	83
Greenhouse gases	58
Water pollution	57
Air pollution	56
Freshwater withdrawals	33

Protein occurs in a wide range of food. On a worldwide basis, plant protein foods contribute over 60% of the per capita supply of protein. In North America, animal-derived foods contribute about 70% of protein sources. Insects are a source of protein in many parts of the world. In parts of Africa, up to 50% of dietary protein derives from insects. It is estimated that more than 2 billion people eat insects daily.

Meat, dairy, eggs, soy, fish, whole grains, and cereals are sources of protein. Examples of food staples and cereal sources of protein, each with a concentration greater than 7%, are (in no particular order) buckwheat, oats, rye, millet, maize (corn), rice, wheat, sorghum, amaranth, and quinoa. Some research highlights game meat as a protein source.

Vegan sources of proteins include legumes, nuts, seeds and fruits. Vegan foods with protein concentrations greater than 7% include soybeans, lentils, kidney beans, white beans, mung beans, chickpeas, cowpeas, lima beans, pigeon peas, lupines, wing beans, almonds, Brazil nuts, cashews, pecans, walnuts, cotton seeds, pumpkin seeds, hemp seeds, sesame seeds, and sunflower seeds.

Photovoltaic-driven microbial protein production uses electricity from solar panels and carbon dioxide from the air to create fuel for microbes, which are grown in bioreactor vats and then processed into dry protein powders. The process makes highly efficient use of land, water and fertiliser.

Plant sources of protein.

People eating a balanced diet do not need protein supplements.

The table below presents food groups as protein sources.

Food source	Lysine	Threonine	Tryptophan	Sulfur-containing amino acids
Legumes	64	38	12	25
Cereals and whole grains	31	32	12	37
Nuts and seeds	45	36	17	46
Fruits	45	29	11	27
Animal	85	44	12	38

Colour key:

  Protein source with highest density of respective amino acid.

  Protein source with lowest density of respective amino acid.

Protein milkshakes, made from protein powder (center) and milk (left), are a common bodybuilding supplement

Protein powders – such as casein, whey, egg, rice, soy and cricket flour– are processed and manufactured sources of protein.

Testing in foods

The classic assays for protein concentration in food are the Kjeldahl method and the Dumas method. These tests determine the total nitrogen in a sample. The only major component of most food which contains nitrogen is protein (fat, carbohydrate and dietary fiber do not contain nitrogen). If the amount of nitrogen is multiplied by a factor depending on the kinds of protein expected in the food the total protein can be determined. This value is known as the "crude protein" content. On food labels the protein is given by the nitrogen multiplied by 6.25, because the average nitrogen content of proteins is about 16%. The Kjeldahl test is typically used because it is the method the AOAC International has adopted and is therefore used by many food standards agencies around the world, though the Dumas method is also approved by some standards organizations.

Accidental contamination and intentional adulteration of protein meals with non-protein nitrogen sources that inflate crude protein content measurements have been known to occur in the food industry for decades. To ensure food quality, purchasers of protein meals routinely conduct quality control tests designed to detect the most common non-protein nitrogen contaminants, such as urea and ammonium nitrate.

In at least one segment of the food industry, the dairy industry, some countries (at least the U.S., Australia, France and Hungary) have adopted "true protein" measurement, as opposed to crude protein measurement, as the standard for payment and testing: "True protein is a measure of only the proteins in milk, whereas crude protein is a measure of all sources of nitrogen and includes nonprotein nitrogen, such as urea, which has no food value to humans. ... Current milk-testing equipment measures peptide bonds, a direct measure of true protein." Measuring peptide bonds in grains has also been put into practice in several countries including Canada, the UK, Australia, Russia and Argentina where near-infrared reflectance (NIR) technology, a type of infrared spectroscopy is used. The Food and Agriculture Organization of the United Nations (FAO) recommends that only amino acid analysis be used to determine protein in, inter alia, foods used as the sole source of nourishment, such as infant formula, but also provides: "When data on amino acids analyses are not available, determination of protein based on total N content by Kjeldahl (AOAC, 2000) or similar method ... is considered acceptable."

The testing method for protein in beef cattle feed has grown into a science over the post-war years. The standard text in the United States, Nutrient Requirements of Beef Cattle, has been through eight editions over at least seventy years. The 1996 sixth edition substituted for the fifth edition's crude protein the concept of "metabolizeable protein", which was defined around the year 2000 as "the true protein absorbed by the intestine, supplied by microbial protein and undegraded intake protein".

The limitations of the Kjeldahl method were at the heart of the Chinese protein export contamination in 2007 and the 2008 China milk scandal in which the industrial chemical melamine was added to the milk or glutens to increase the measured "protein".

Protein quality

Further information: Protein quality and Amino acid score

The most important aspect and defining characteristic of protein from a nutritional standpoint is its amino acid composition. There are multiple systems which rate proteins by their usefulness to an organism based on their relative percentage of amino acids and, in some systems, the digestibility of the protein source. They include biological value, net protein utilization, and PDCAAS (Protein Digestibility Corrected Amino Acids Score) which was developed by the FDA as a modification of the Protein efficiency ratio (PER) method. The PDCAAS rating was adopted by the US Food and Drug Administration (FDA) and the Food and Agricultural Organization of the United Nations/World Health Organization (FAO/WHO) in 1993 as "the preferred 'best'" method to determine protein quality. These organizations have suggested that other methods for evaluating the quality of protein are inferior. In 2013 FAO proposed changing to Digestible Indispensable Amino Acid Score.

Digestion

Most proteins are decomposed to single amino acids by digestion in the gastro-intestinal tract.

Digestion typically begins in the stomach when pepsinogen is converted to pepsin by the action of hydrochloric acid, and continued by trypsin and chymotrypsin in the small intestine. Before the absorption in the small intestine, most proteins are already reduced to single amino acid or peptides of several amino acids. Most peptides longer than four amino acids are not absorbed. Absorption into the intestinal absorptive cells is not the end. There, most of the peptides are broken into single amino acids.

Absorption of the amino acids and their derivatives into which dietary protein is degraded is done by the gastrointestinal tract. The absorption rates of individual amino acids are highly dependent on the protein source; for example, the digestibilities of many amino acids in humans, the difference between soy and milk proteins and between individual milk proteins, beta-lactoglobulin and casein. For milk proteins, about 50% of the ingested protein is absorbed between the stomach and the jejunum and 90% is absorbed by the time the digested food reaches the ileum. Biological value (BV) is a measure of the proportion of absorbed protein from a food which becomes incorporated into the proteins of the organism's body.

Newborn

Newborns of mammals are exceptional in protein digestion and assimilation in that they can absorb intact proteins at the small intestine. This enables passive immunity, i.e., transfer of immunoglobulins from the mother to the newborn, via milk.

Dietary requirements

An education campaign launched by the United States Department of Agriculture about 100 years ago, on cottage cheese as a lower-cost protein substitute for meat.

Considerable debate has taken place regarding issues surrounding protein intake requirements. The amount of protein required in a person's diet is determined in large part by overall energy intake, the body's need for nitrogen and essential amino acids, body weight and composition, rate of growth in the individual, physical activity level, the individual's energy and carbohydrate intake, and the presence of illness or injury. Physical activity and exertion as well as enhanced muscular mass increase the need for protein. Requirements are also greater during childhood for growth and development, during pregnancy, or when breastfeeding in order to nourish a baby or when the body needs to recover from malnutrition or trauma or after an operation.

Dietary recommendations

According to US & Canadian Dietary Reference Intake guidelines, women aged 19–70 need to consume 46 grams of protein per day while men aged 19–70 need to consume 56 grams of protein per day to minimize risk of deficiency. These Recommended Dietary Allowances (RDAs) were calculated based on 0.8 grams protein per kilogram body weight and average body weights of 57 kg (126 pounds) and 70 kg (154 pounds), respectively. However, this recommendation is based on structural requirements but disregards use of protein for energy metabolism. This requirement is for a normal sedentary person. In the United States, average protein consumption is higher than the RDA. According to results of the National Health and Nutrition Examination Survey (NHANES 2013-2014), average protein consumption for women ages 20 and older was 69.8 grams and for men 98.3 grams/day.

Active people

Several studies have concluded that active people and athletes may require elevated protein intake (compared to 0.8 g/kg) due to increase in muscle mass and sweat losses, as well as need for body repair and energy source. Suggested amounts vary from 1.2 to 1.4 g/kg for those doing endurance exercise to as much as 1.6-1.8 g/kg for strength exercise, while a proposed maximum daily protein intake would be approximately 25% of energy requirements i.e. approximately 2 to 2.5 g/kg. However, many questions still remain to be resolved.

In addition, some have suggested that athletes using restricted-calorie diets for weight loss should further increase their protein consumption, possibly to 1.8–2.0 g/kg, in order to avoid loss of lean muscle mass.

Aerobic exercise protein needs

Endurance athletes differ from strength-building athletes in that endurance athletes do not build as much muscle mass from training as strength-building athletes do. Research suggests that individuals performing endurance activity require more protein intake than sedentary individuals so that muscles broken down during endurance workouts can be repaired. Although the protein requirement for athletes still remains controversial (for instance see Lamont, Nutrition Research Reviews, pages 142 - 149, 2012), research does show that endurance athletes can benefit from increasing protein intake because the type of exercise endurance athletes participate in still alters the protein metabolism pathway. The overall protein requirement increases because of amino acid oxidation in endurance-trained athletes. Endurance athletes who exercise over a long period (2–5 hours per training session) use protein as a source of 5–10% of their total energy expended. Therefore, a slight increase in protein intake may be beneficial to endurance athletes by replacing the protein lost in energy expenditure and protein lost in repairing muscles. One review concluded that endurance athletes may increase daily protein intake to a maximum of 1.2–1.4 g per kg body weight.

Anaerobic exercise protein needs

Research also indicates that individuals performing strength training activity require more protein than sedentary individuals. Strength-training athletes may increase their daily protein intake to a maximum of 1.4–1.8 g per kg body weight to enhance muscle protein synthesis, or to make up for the loss of amino acid oxidation during exercise. Many athletes maintain a high-protein diet as part of their training. In fact, some athletes who specialize in anaerobic sports (e.g., weightlifting) believe a very high level of protein intake is necessary, and so consume high protein meals and also protein supplements.

Special populations

Protein allergies

Main article: Food allergy

A food allergy is an abnormal immune response to proteins in food. The signs and symptoms may range from mild to severe. They may include itchiness, swelling of the tongue, vomiting, diarrhea, hives, trouble breathing, or low blood pressure. These symptoms typically occurs within minutes to one hour after exposure. When the symptoms are severe, it is known as anaphylaxis. The following eight foods are responsible for about 90% of allergic reactions: cow's milk, eggs, wheat, shellfish, fish, peanuts, tree nuts and soy.

Chronic kidney disease

While there is no conclusive evidence that a high protein diet can cause chronic kidney disease, there is a consensus that people with this disease should decrease consumption of protein. According to one 2009 review updated in 2018, people with chronic kidney disease who reduce protein consumption have less likelihood of progressing to end stage kidney disease. Moreover, people with this disease while using a low protein diet (0.6 g/kg/d - 0.8 g/kg/d) may develop metabolic compensations that preserve kidney function, although in some people, malnutrition may occur.

Phenylketonuria

Individuals with phenylketonuria (PKU) must keep their intake of phenylalanine - an essential amino acid - extremely low to prevent a mental disability and other metabolic complications. Phenylalanine is a component of the artificial sweetener aspartame, so people with PKU need to avoid low calorie beverages and foods with this ingredient.

Maple syrup urine disease

Maple syrup urine disease is associated with genetic anomalies in the metabolism of branched-chain amino acids (BCAAs). They have high blood levels of BCAAs and must severely restrict their intake of BCAAs in order to prevent mental retardation and death. The amino acids in question are leucine, isoleucine and valine. The condition gets its name from the distinctive sweet odor of affected infants' urine. Children of Amish, Mennonite, and Ashkenazi Jewish descent have a high prevalence of this disease compared to other populations.

Excess consumption

See also: Protein poisoning

The U.S. and Canadian Dietary Reference Intake review for protein concluded that there was not sufficient evidence to establish a Tolerable upper intake level, i.e., an upper limit for how much protein can be safely consumed.

When amino acids are in excess of needs, the liver takes up the amino acids and deaminates them, a process converting the nitrogen from the amino acids into ammonia, further processed in the liver into urea via the urea cycle. Excretion of urea occurs via the kidneys. Other parts of the amino acid molecules can be converted into glucose and used for fuel. When food protein intake is periodically high or low, the body tries to keep protein levels at an equilibrium by using the "labile protein reserve" to compensate for daily variations in protein intake. However, unlike body fat as a reserve for future caloric needs, there is no protein storage for future needs.

Excessive protein intake may increase calcium excretion in urine, occurring to compensate for the pH imbalance from oxidation of sulfur amino acids. This may lead to a higher risk of kidney stone formation from calcium in the renal circulatory system. One meta-analysis reported no adverse effects of higher protein intakes on bone density. Another meta-analysis reported a small decrease in systolic and diastolic blood pressure with diets higher in protein, with no differences between animal and plant protein.

High protein diets have been shown to lead to an additional 1.21 kg of weight loss over a period of 3 months versus a baseline protein diet in a meta-analysis. Benefits of decreased body mass index as well as HDL cholesterol were more strongly observed in studies with only a slight increase in protein intake rather where high protein intake was classified as 45% of total energy intake. Detrimental effects to cardiovascular activity were not observed in short-term diets of 6 months or less. There is little consensus on the potentially detrimental effects to healthy individuals of a long-term high protein diet, leading to caution advisories about using high protein intake as a form of weight loss.

The 2015–2020 Dietary Guidelines for Americans (DGA) recommends that men and teenage boys increase their consumption of fruits, vegetables and other under-consumed foods, and that a means of accomplishing this would be to reduce overall intake of protein foods. The 2015 - 2020 DGA report does not set a recommended limit for the intake of red and processed meat. While the report acknowledges research showing that lower intake of red and processed meat is correlated with reduced risk of cardiovascular diseases in adults, it also notes the value of nutrients provided from these meats. The recommendation is not to limit intake of meats or protein, but rather to monitor and keep within daily limits the sodium (< 2300 mg), saturated fats (less than 10% of total calories per day), and added sugars (less than 10% of total calories per day) that may be increased as a result of consumption of certain meats and proteins. While the 2015 DGA report does advise for a reduced level of consumption of red and processed meats, the 2015-2020 DGA key recommendations recommend that a variety of protein foods be consumed, including both vegetarian and non-vegetarian sources of protein.

Protein deficiency

A child in Nigeria during the Biafra War suffering from kwashiorkor – one of the three protein energy malnutrition ailments afflicting over 10 million children in developing countries.

 

Main article: Protein-energy malnutrition

Protein deficiency and malnutrition (PEM) can lead to variety of ailments including Intellectual disability and kwashiorkor. Symptoms of kwashiorkor include apathy, diarrhea, inactivity, failure to grow, flaky skin, fatty liver, and edema of the belly and legs. This edema is explained by the action of lipoxygenase on arachidonic acid to form leukotrienes and the normal functioning of proteins in fluid balance and lipoprotein transport.

PEM is fairly common worldwide in both children and adults and accounts for 6 million deaths annually. In the industrialized world, PEM is predominantly seen in hospitals, is associated with disease, or is often found in the elderly.

Social networking service

From Wikipedia, the free encyclopedia

https://en.wikipedia.org/wiki/Social_networking_service 

 

A social networking service or SNS (sometimes called a social networking site) is an online platform which people use to build social networks or social relationships with other people who share similar personal or career content, interests, activities, backgrounds or real-life connections.

Social networking services vary in format and the number of features. They can incorporate a range of new information and communication tools, operating on desktops and on laptops, on mobile devices such as tablet computers and smartphones. This may feature digital photo/video/sharing and diary entries online (blogging). Online community services are sometimes considered social-network services by developers and users, though in a broader sense, a social-network service usually provides an individual-centered service whereas online community services are groups centered. Generally defined as "websites that facilitate the building of a network of contacts in order to exchange various types of content online," social networking sites provide a space for interaction to continue beyond in-person interactions. These computer mediated interactions link members of various networks and may help to create, sustain and develop new social and professional relationships.

Social networking sites allow users to share ideas, digital photos and videos, posts, and to inform others about online or real-world activities and events with people within their social network. While in-person social networking – such as gathering in a village market to talk about events – has existed since the earliest development of towns, the web enables people to connect with others who live in different locations across the globe (dependent on access to an internet connection to do so). Depending on the social media platform, members may be able to contact any other member. In other cases, members can contact anyone they have a connection to, and subsequently anyone that contact has a connection to, and so on. The success of social networking services can be seen in their dominance in society today, with Facebook having a massive 2.13 billion active monthly users and an average of 1.4 billion daily active users in 2017. LinkedIn, a career-oriented social-networking service, generally requires that a member personally know another member in real life before they contact them online. Some services require members to have a preexisting connection to contact other members. With COVID-19, Zoom, a videoconferencing platform, has taken an integral place to connect people located around the world and facilitate many online environments such as school, university, work and government meetings.

The main types of social networking services contain category places (such as age or occupation or religion), means to connect with friends (usually with self-description pages), and a recommendation system linked to trust. One can categorize social-network services into four types:

• socialization social network services used primarily for socializing with existing friends (e.g., Facebook, Instagram)
• online social networks are decentralized and distributed computer networks where users communicate with each other through internet services.
• networking social network services used primarily for non-social interpersonal communication (e.g., LinkedIn, a career- and employment-oriented site)
• social navigation social network services used primarily for helping users to find specific information or resources (e.g., Goodreads for books, Reddit)

There have been attempts to standardize these services to avoid the need to duplicate entries of friends and interests (see the FOAF standard). A study reveals that India recorded world's largest growth in terms of social media users in 2013. A 2013 survey found that 73% of U.S. adults use social-networking sites.

Definition

There is a variety of social networking services available online. However, most incorporate common features:

• social networking services are, Internet-based applications
• user-generated content (UGC) is the lifeblood of social networking services.
• users create service-specific profiles for the site or app that are designed and maintained by the SNS organization
• social networking services facilitate the development of online social networks by connecting a user's profile with those of other individuals or groups.

A challenge of definition

The variety and evolving range of stand-alone and built-in social networking services in the online space introduces a challenge of definition. Furthermore, the idea that these services are defined by their ability to bring people together provides too broad a definition. Such a broad definition would suggest that the telegraph and telephone were social networking services – the Internet technologies scholars are intending to describe. The terminology is also unclear, with some referring to social networking services as social media.

Attempting definition

An attempt in 2015 at providing a clear definition reviewed the prominent literature in the area and identified four commonalities unique to current social networking services:

1. social networking services are interactive Web 2.0 Internet-based applications,
2. user-generated content (UGC), such as user-submitted digital photos, text posts, "tagging", online comments, and diary-style "web logs" (blogs), is the lifeblood of the SNS organism,
3. users create service-specific profiles for the site or app that are designed and maintained by the SNS organization, and
4. social networking services facilitate the development of social networks online by connecting a user's profile with those of other individuals or groups.

Offline and online social networking services

Differences between offline and online social networking services

Characteristic	Offline social network	Online social network
Degree centrality	While the number of cognitively manageable ties is limited to about 150, most people report having 14–56 ties at average	Huge number of ties technologically possible, but average number is limited, e.g., Facebook: 395
Symmetry	Usually symmetric (reciprocal behavior)	Symmetric (e.g., Instagram, LinkedIn, XING) and asymmetric (e.g., Twitter)
Affect	Positive (92–97%) and negative (3–8%) tie relationships can be managed using high sophisticated coordination mechanisms such as argumentation and negotiation	Except through blocking (e.g., Twitter) or hiding (e.g., Facebook) limited support to deal with negative tie relationships
Strength	2–8 strong ties and 12–48 weak/latent ties on average	9–37 strong ties and 68–131 weak/latent ties on average
Dynamic of change	Low due to manual interaction	High because of technological support

History

The potential for computer networking to facilitate newly improved forms of computer-mediated social interaction was suggested early on. Efforts to support social networks via computer-mediated communication were made in many early online services, including Usenet, ARPANET, LISTSERV, and bulletin board services (BBS). Many prototypical features of social networking sites were also present in online services such as The Source, Delphi, America Online, Prodigy, CompuServe, ChatNet, and The WELL.

Early social networking on the World Wide Web began in the form of generalized online communities such as Theglobe.com (1995), Geocities (1994) and Tripod.com (1995). Many of these early communities focused on bringing people together to interact with each other through chat rooms and encouraged users to share personal information and ideas via personal web pages by providing easy-to-use publishing tools and free or inexpensive web space. Some communities – such as Classmates.com – took a different approach by simply having people link to each other via email addresses. PlanetAll started in 1996.

In the late 1990s, user profiles became a central feature of social networking sites, allowing users to compile lists of "friends" and search for other users with similar interests. New social networking methods were developed by the end of the 1990s, and many sites began to develop more advanced features for users to find and manage friends. Open Diary, a community for online diarists, invented both friends-only content and the reader comment, two features of social networks important to user interaction.

This newer generation of social networking sites began to flourish with the emergence of SixDegrees in 1997, followed by Open Diary in 1998, Mixi in 1999, Makeoutclub in 2000, Hub Culture in 2002, Friendster and Canada's first online social network Nexopia in 2003, and soon became part of the Internet mainstream. However, thanks to the nation's high Internet penetration rate, the first mass social networking site was the South Korean service, Cyworld, launched as a blog-based site in 1999 and social networking features added in 2001. It also became one of the first companies to profit from the sale of virtual goods. Friendster was followed by MySpace and LinkedIn the same year, and eventually Bebo. Friendster became very popular in the Pacific Islands. Orkut became the first popular social networking service in Brazil (although most of its very first users were from the United States) and quickly grew in popularity in India (Madhavan, 2007). Attesting to the rapid increase in social networking sites' popularity, by 2005, it was reported that Myspace was getting more page views than Google. Facebook, launched in 2004, became the largest social networking site in the world in early 2009. Facebook was first introduced as a Harvard social networking site, expanding to other universities and eventually, anyone. The term social media was introduced and soon became widespread.

Social impact

See also: Social impact of the Internet § Social networking and entertainment

Web-based social networking services make it possible to connect people who share interests and activities across political, economic, and geographic borders. Through e-mail and instant messaging, online communities are created where a gift economy and reciprocal altruism are encouraged through cooperation. Information is suited to a gift economy, as information is a nonrival good and can be gifted at practically no cost. Scholars have noted that the term "social" cannot account for technological features of the social network platforms alone. Hence, the level of network sociability should determine by the actual performances of its users. According to the communication theory of uses and gratifications, an increasing number of individuals are looking to the Internet and social media to fulfill cognitive, affective, personal integrative, social integrative, and tension free needs. With Internet technology as a supplement to fulfill needs, it is in turn affecting every day life, including relationships, school, church, entertainment, and family. Companies are using social media as a way to learn about potential employees' personalities and behavior. In numerous situations, a candidate who might otherwise have been hired has been rejected due to offensive or otherwise unseemly photos or comments posted to social networks or appearing on a newsfeed.

Facebook and other social networking tools are increasingly the aims of scholarly research. Scholars in many fields have begun to investigate the impact of social networking sites, investigating how such sites may play into issues of identity, politics, privacy, social capital, youth culture, and education. Research has also suggested that individuals add offline friends on Facebook to maintain contact and often this blurs the lines between work and home lives. Users from around the world also utilise social networking sites as an alternative news source. While social networking sites have arguably changed how we access the news, users tend to have mixed opinions about the reliability of content accessed through these sites.

According to a study in 2015, 63% of the users of Facebook or Twitter in the USA consider these networks to be their main source of news, with entertainment news being the most seen. In the times of breaking news, Twitter users are more likely to stay invested in the story. In some cases when the news story is more political, users may be more likely to voice their opinion on a linked Facebook story with a comment or like, while Twitter users will just follow the site's feed and retweet the article. In online social networks, the veracity and reliability of news may be diminished due to the absence of traditional media gatekeepers.

A 2015 study shows that 85% of people aged 18 to 34 use social networking sites for their purchase decision making. While over 65% of people aged 55 and over-rely on word of mouth. Several websites are beginning to tap into the power of the social networking model for philanthropy. Such models provide a means for connecting otherwise fragmented industries and small organizations without the resources to reach a broader audience with interested users. Social networks are providing a different way for individuals to communicate digitally. These communities of hypertexts allow for the sharing of information and ideas, an old concept placed in a digital environment. In 2011, HCL Technologies conducted research that showed that 50% of British employers had banned the use of social networking sites/services during office hours.

Research has provided us with mixed results as to whether or not a person's involvement in social networking can affect their feelings of loneliness. Studies have indicated that how a person chooses to use social networking can change their feelings of loneliness in either a negative or positive way. Some companies with mobile workers have encouraged their workers to use social networking to feel connected. Educators are using social networking to stay connected with their students whereas individuals use it to stay connected with their close relationships. Each social networking user is able to create a community that centers around a personal identity they choose to create online. In his book Digital Identities: Creating and Communicating the Online Self, Rob Cover argues that social networking's foundation in Web 2.0, high-speed networking shifts online representation to one which is both visual and relational to other people, complexifying the identity process for younger people and creating new forms of anxiety. In 2016, news reports stated that excessive usage of SNS sites may be associated with an increase in the rates of depression, to almost triple the rate for non-SNS users. Experts worldwide have said that 2030 people who use SNS more have higher levels of depression than those who use SNS less. At least one study went as far as to conclude that the negative effects of Facebook usage are equal to or greater than the positive effects of face-to-face interactions.

According to a recent article from Computers in Human Behavior, Facebook has also been shown to lead to issues of social comparison. Users are able to select which photos and status updates to post, allowing them to portray their lives in acclamatory manners. These updates can lead to other users feeling like their lives are inferior by comparison. Users may feel especially inclined to compare themselves to other users with whom they share similar characteristics or lifestyles, leading to a fairer comparison. Motives for these comparisons can be associated with the goals of improving oneself by looking at profiles of people who one feels are superior, especially when their lifestyle is similar and possible. One can also self-compare to make oneself feel superior to others by looking at the profiles of users who one believes to be worse off. However, a study by the Harvard Business Review shows that these goals often lead to negative consequences, as use of Facebook has been linked with lower levels of well-being; mental health has been shown to decrease due to the use of Facebook. Computers in Human Behavior emphasizes that these feelings of poor mental health have been suggested to cause people to take time off from their Facebook accounts; this action is called "Facebook Fatigue" and has been common in recent years.

Usage of social networking has contributed to a new form of abusive communication, and academic research has highlighted a number of social-technological explanations for this behaviour. These including the anonymity afforded by interpersonal communications, factors that include boredom or attention seeking, or the result of more polarised online debate. The impact in this abuse has found impacts through the prevalence of online cyberbullying, and online trolling. There has also been a marked increase in political violence and abuse through social media platforms. For instance, one study by Ward and McLoughlin found that 2.57% of all messages sent to UK MPs on Twitter were found to contain abusive messages.

Features

Typical features

According to boyd and Ellison's (2007) article, "Why Youth (Heart) Social Network Sites: The Role of Networked Publics in Teenage Social Life", social networking sites share a variety of technical features that allow individuals to: construct a public/semi-public profile, articulate a list of other users that they share a connection with, and view their list of connections within the system. The most basic of these are visible profiles with a list of "friends" who are also users of the site. In an article entitled "Social Network Sites: Definition, History, and Scholarship," boyd and Ellison adopt Sunden's (2003) description of profiles as unique pages where one can "type oneself into being". A profile is generated from answers to questions, such as age, location, interests, etc. Some sites allow users to upload pictures, add multimedia content or modify the look and feel of the profile. Others, e.g., Facebook, allow users to enhance their profile by adding modules or "Applications". Many sites allow users to post blog entries, search for others with similar interests and compile and share lists of contacts. User profiles often have a section dedicated to comments from friends and other users. To protect user privacy, social networks typically have controls that allow users to choose who can view their profile, contact them, add them to their list of contacts, and so on.

Additional features

There is a trend towards more interoperability between social networks led by technologies such as OpenID and OpenSocial. In most mobile communities, mobile phone users can now create their own profiles, make friends, participate in chat rooms, create chat rooms, hold private conversations, share photos and videos, and share blogs by using their mobile phone. Some companies provide wireless services that allow their customers to build their own mobile community and brand it; one of the most popular wireless services for social networking in North America and Nepal is Facebook Mobile. Recently, twitter has also introduced fact check labels to combat misinformation which was primarily spread due to the coronavirus but also has had an impact on debunking false claims by Donald Trump in the 2020 election.

Social media platforms may allow users to change their user name (or "handle", distinct from the "display name"), which could change the URL to their profile. Users are advised to do so with caution, since it could break back links from others' posts and comments depending on implementation, and external back links.

Emerging trends

The things you share are things that make you look good, things which you are happy to tie into your identity.

— Hilary Mason, chief data scientist, bitly, VentureBeat, 2012

While the popularity of social networking consistently rises, new uses for the technology are frequently being observed. Today's technologically savvy population requires convenient solutions to their daily needs. At the forefront of emerging trends in social networking sites is the concept of "real-time web" and "location-based". Real-time allows users to contribute contents, which is then broadcast as it is being uploaded—the concept is analogous to live radio and television broadcasts. Twitter set the trend for "real-time" services, wherein users can broadcast to the world what they are doing, or what is on their minds within a 140-character limit. Facebook followed suit with their "Live Feed" where users' activities are streamed as soon as it happens. While Twitter focuses on words, Clixtr, another real-time service, focuses on group photo sharing wherein users can update their photo streams with photos while at an event. Facebook, however, remains the largest photo sharing site with over 250 billion photos as of September 2013. In April 2012, the image-based social media network Pinterest had become the third largest social network in the United States.

Companies have begun to merge business technologies and solutions, such as cloud computing, with social networking concepts. Instead of connecting individuals based on social interest, companies are developing interactive communities that connect individuals based on shared business needs or experiences. Many provide specialized networking tools and applications that can be accessed via their websites, such as LinkedIn. Others companies, such as Monster.com, have been steadily developing a more "socialized" feel to their career center sites to harness some of the power of social networking sites. These more business related sites have their own nomenclature for the most part but the most common naming conventions are "Vocational Networking Sites" or "Vocational Media Networks", with the former more closely tied to individual networking relationships based on social networking principles.

Foursquare gained popularity as it allowed for users to check into places that they are frequenting at that moment. Gowalla is another such service that functions in much the same way that Foursquare does, leveraging the GPS in phones to create a location-based user experience. Clixtr, though in the real-time space, is also a location-based social networking site, since events created by users are automatically geotagged, and users can view events occurring nearby through the Clixtr iPhone app. Recently, Yelp announced its entrance into the location-based social networking space through check-ins with their mobile app; whether or not this becomes detrimental to Foursquare or Gowalla is yet to be seen, as it is still considered a new space in the Internet technology industry.

One popular use for this new technology is social networking between businesses. Companies have found that social networking sites such as Facebook and Twitter are great ways to build their brand image. According to Jody Nimetz, author of Marketing Jive, there are five major uses for businesses and social media: to create brand awareness, as an online reputation management tool, for recruiting, to learn about new technologies and competitors, and as a lead generation tool to intercept potential prospects. These companies are able to drive traffic to their own online sites while encouraging their consumers and clients to have discussions on how to improve or change products or services. As of September 2013, 71% of online adults use Facebook, 17% use Instagram, 21% use Pinterest, and 22% use LinkedIn.

Niche networks

In 2012, it was reported that in the past few years, the niche social network has steadily grown in popularity, thanks to better levels of user interaction and engagement. In 2012, a survey by Reuters and research firm Ipsos found that one in three users were getting bored with Facebook and in 2014 the GlobalWebIndex found that this figured had risen to almost 50%. The niche social network offers a specialized space that's designed to appeal to a very specific market with a clearly defined set of needs. Where once the streams of social minutia on networks such as Facebook and Twitter were the ultimate in online voyeurism, now users are looking for connections, community and shared experiences. Social networks that tap directly into specific activities, hobbies, tastes, and lifestyles are seeing a consistent rise in popularity.

Science

One other use that is being discussed is the use of social networks in the science communities. Julia Porter Liebeskind et al. have published a study on how new biotechnology firms are using social networking sites to share exchanges in scientific knowledge. They state in their study that by sharing information and knowledge with one another, they are able to "increase both their learning and their flexibility in ways that would not have been possible within a self-contained hierarchical organization". Social networking is allowing scientific groups to expand their knowledge base and share ideas, and without these new means of communicating their theories might become "isolated and irrelevant". Researchers use social networks frequently to maintain and develop professional relationships. They are interested in consolidating social ties and professional contact, keeping in touch with friends and colleagues and seeing what their own contacts are doing. This can be related to their need to keep updated on the activities and events of their friends and colleagues in order to establish collaborations on common fields of interest and knowledge sharing.

Social networks are also used to communicate scientists research results and as a public communication tool and to connect people who share the same professional interests, their benefits can vary according to the discipline. The most interesting aspects of social networks for professional purposes are their potentialities in terms of dissemination of information and the ability to reach and multiple professional contacts exponentially. Social networks like Academia.edu, LinkedIn, Facebook, and ResearchGate give the possibility to join professional groups and pages, to share papers and results, publicize events, to discuss issues and create debates. Academia.edu is extensively used by researchers, where they follow a combination of social networking and scholarly norms. ResearchGate is also widely used by researchers, especially to disseminate and discuss their publications, where it seems to attract an audience that it wider than just other scientists. The usage of Research Gate and Academia in different academic communities has increasingly been studied in recent years.

Education

The advent of social networking platforms may also be impacting the ways in which learners engage with technology in general. For a number of years, Prensky's (2001) dichotomy between Digital Natives and Digital Immigrants has been considered a relatively accurate representation of the ease with which people of a certain age range—in particular those born before and after 1980—use technology. Prensky's theory has been largely disproved, however, and not least on account of the burgeoning popularity of social networking sites and other metaphors such as White and Le Cornu's "Visitors" and "Residents" (2011) are greater currency. The use of online social networks by school libraries is also increasingly prevalent and they are being used to communicate with potential library users, as well as extending the services provided by individual school libraries. Social networks and their educational uses are of interest to many researchers. According to Livingstone and Brake (2010), "Social networking sites, like much else on the Internet, represent a moving target for researchers and policymakers." Pew Research Center project, called Pew Internet, did a USA-wide survey in 2009 and in 2010 February published that 47% of American adults use a social networking website. Same survey found that 73% of online teenagers use SNS, which is an increase from 65% in 2008, 55% in 2006. Recent studies have shown that social network services provide opportunities within professional education, curriculum education, and learning. However, there are constraints in this area. Researches, especially in Africa, have disclosed that the use of social networks among students has been known to affect their academic life negatively. This is buttressed by the fact that their use constitutes distractions, as well as that the students tend to invest a good deal of time in the use of such technologies.

Albayrak and Yildirim (2015) examined the educational use of social networking sites. They investigated students' involvement in Facebook as a Course Management System (CMS) and the findings of their study support that Facebook as a CMS has the potential to increase student involvement in discussions and out-of-class communication among instructors and students.

Professional use

Further information: Professional network service

Professional use of social networking services refers to the employment of a network site to connect with other professionals within a given field of interest. These type of social networking services are referred to as "Career-oriented social networking markets (CSNM)". LinkedIn is one example and is a social networking website geared towards companies and industry professionals looking to make new business contacts or keep in touch with previous co-workers, affiliates, and clients. LinkedIn provides not only a professional social use but also encourages people to inject their personality into their profile – making it more personal than a resume. Similar websites to linkedin (also geared towards companies and industry professionals looking for work opportunities) to connect include AngelList, XING, Goodwall, The Dots, Jobcase, Opportunity, Bark.com, ... Various freelance marketplace websites (which focus on freelance work) also exist. There are also a number of other employment websites focused on international volunteering, notably VolunteerMatch, Idealist.org and All for Good. National WWOOF networks finally allow for searching for homestays on organic farms.

Now other social network sites are also being used in this manner. Twitter has become [a] mainstay for professional development as well as promotion and online SNSs support both the maintenance of existing social ties and the formation of new connections. Much of the early research on online communities assume that individuals using these systems would be connecting with others outside their preexisting social group or location, liberating them to form communities around shared interests, as opposed to shared geography. Other researchers have suggested that the professional use of network sites produce "social capital". For individuals, social capital allows a person to draw on resources from other members of the networks to which he or she belongs. These resources can take the form of useful information, personal relationships, or the capacity to organize groups. As well, networks within these services also can be established or built by joining special interest groups that others have made, or creating one and asking others to join.

Curriculum use

According to Doering, Beach, and O'Brien, a future English curriculum needs to recognize a significant shift in how adolescents are communicating with each other. Curriculum uses of social networking services can also include sharing curriculum-related resources. Educators tap into user-generated content to find and discuss curriculum-related content for students. Responding to the popularity of social networking services among many students, teachers are increasingly using social networks to supplement teaching and learning in traditional classroom environments. This way they can provide new opportunities for enriching existing curriculum through creative, authentic and flexible, non-linear learning experiences. Some social networks, such as English, baby! and LiveMocha, are explicitly education-focused and couple instructional content with an educational peer environment. The new Web 2.0 technologies built into most social networking services promote conferencing, interaction, creation, research on a global scale, enabling educators to share, remix, and repurpose curriculum resources. In short, social networking services can become research networks as well as learning networks.

Learning use

Educators and advocates of new digital literacies are confident that social networking encourages the development of transferable, technical, and social skills of value in formal and informal learning. In a formal learning environment, goals or objectives are determined by an outside department or agency. Tweeting, instant messaging, or blogging enhances student involvement. Students who would not normally participate in class are more apt to partake through social network services. Networking allows participants the opportunity for just-in-time learning and higher levels of engagement. The use of SNSs allow educators to enhance the prescribed curriculum. When learning experiences are infused into a website student utilize every day for fun, students realize that learning can and should be a part of everyday life. It does not have to be separate and unattached.

Informal learning consists of the learner setting the goals and objectives. It has been claimed that media no longer just influence human culture; they are human culture. With such a high number of users between the ages of 13–18, a number of skills are developed. Participants hone technical skills in choosing to navigate through social networking services. This includes elementary items such as sending an instant message or updating a status. The development of new media skills are paramount in helping youth navigate the digital world with confidence.

Social networking services foster learning through what Jenkins (2006) describes as a "participatory culture". A participatory culture consists of a space that allows engagement, sharing, mentoring, and an opportunity for social interaction. Participants of social network services avail of this opportunity. Informal learning, in the forms of participatory and social learning online, is an excellent tool for teachers to sneak in material and ideas that students will identify with and therefore, in a secondary manner, students will learn skills that would normally be taught in a formal setting in the more interesting and engaging environment of social learning. Sites like Twitter provide students with the opportunity to converse and collaborate with others in real time.

Social networking services provide a virtual "space" for learners. James Gee (2004) suggests that affinity spaces instantiate participation, collaboration, distribution, dispersion of expertise, and relatedness. Registered users share and search for knowledge which contributes to informal learning.

Constraints

In the past, social networking services were viewed as a distraction and offered no educational benefit. Blocking these social networks was a form of protection for students against wasting time, bullying, and invasions of privacy. In an educational setting, Facebook, for example, is seen by many instructors and educators as a frivolous, time-wasting distraction from schoolwork, and it is not uncommon to be banned in junior high or high school computer labs. Cyberbullying has become an issue of concern with social networking services. According to the UK Children Go Online survey of 9- to 19-year-olds, it was found that a third have received bullying comments online. To avoid this problem, many school districts/boards have blocked access to social networking services such as Facebook, MySpace, and Twitter within the school environment. Social networking services often include a lot of personal information posted publicly, and many believe that sharing personal information is a window into privacy theft. Schools have taken action to protect students from this. It is believed that this outpouring of identifiable information and the easy communication vehicle that social networking services open the door to sexual predators, cyberbullying, and cyberstalking. In contrast, however, 70% of social media using teens and 85% of adults believe that people are mostly kind to one another on social network sites.

Recent research suggests that there has been a shift in blocking the use of social networking services. In many cases, the opposite is occurring as the potential of online networking services is being realized. It has been suggested that if schools block them [social networking services], they are preventing students from learning the skills they need. Banning social networking [...] is not only inappropriate but also borderline irresponsible when it comes to providing the best educational experiences for students. Schools and school districts have the option of educating safe media usage as well as incorporating digital media into the classroom experience, thus preparing students for the literacy they will encounter in the future.

Positive correlates

A cyberpsychology research study conducted by Australian researchers demonstrated that a number of positive psychological outcomes are related to Facebook use. These researchers established that people can derive a sense of social connectedness and belongingness in the online environment. Importantly, this online social connectedness was associated with lower levels of depression and anxiety, and greater levels of subjective well-being. These findings suggest that the nature of online social networking determines the outcomes of online social network use.

Grassroots organizing

Social networks are being used by activists as a means of low-cost grassroots organizing. Extensive use of an array of social networking sites enabled organizers of 2009 National Equality March to mobilize an estimated 200,000 participants to march on Washington with a cost savings of up to 85% per participant over previous methods. The August 2011 England riots were similarly considered to have escalated and been fuelled by this type of grassroots organization.

Employment

A rise in social network use is being driven by college students using the services to network with professionals for internship and job opportunities. Many studies have been done on the effectiveness of networking online in a college setting, and one notable one is by Phipps Arabie and Yoram Wind published in Advances in Social Network Analysis. Many schools have implemented online alumni directories which serve as makeshift social networks that current and former students can turn to for career advice. However, these alumni directories tend to suffer from an oversupply of advice-seekers and an undersupply of advice providers. One new social networking service, Ask-a-peer, aims to solve this problem by enabling advice seekers to offer modest compensation to advisers for their time. LinkedIn is also another great resource. It helps alumni, students and unemployed individuals look for work. They are also able to connect with others professionally and network with companies.

In addition, employers have been found to use social network sites to screen job candidates.

Hosting service

A social network hosting service is a web hosting service that specifically hosts the user creation of web-based social networking services, alongside related applications.

Trade network

A social trade network is a service that allows participants interested in specific trade sectors to share related contents and personal opinions.

Business model

Few social networks charge money for membership. In part, this may be because social networking is a relatively new service, and the value of using them has not been firmly established in customers' minds. Companies such as Myspace and Facebook sell online advertising on their site. Their business model is based upon large membership count, and charging for membership would be counterproductive. Some believe that the deeper information that the sites have on each user will allow much better targeted advertising than any other site can currently provide. In recent times, Apple has been critical of the Google and Facebook model, in which users are defined as product and a commodity, and their data being sold for marketing revenue. Social networks operate under an autonomous business model, in which a social network's members serve dual roles as both the suppliers and the consumers of content. This is in contrast to a traditional business model, where the suppliers and consumers are distinct agents. Revenue is typically gained in the autonomous business model via advertisements, but subscription-based revenue is possible when membership and content levels are sufficiently high.

Social interaction

People use social networking sites for meeting new friends, finding old friends, or locating people who have the same problems or interests they have, called niche networking. More and more relationships and friendships are being formed online and then carried to an offline setting. Psychologist and University of Hamburg professor Erich H. Witte says that relationships which start online are much more likely to succeed. In this regard, there are studies which predict tie strength among the friends on social networking websites. One online dating site claims that 2% of all marriages begin at its site, the equivalent of 236 marriages a day. Other sites claim one in five relationships begin online.

Users do not necessarily share with others the content which is of most interest to them, but rather that which projects a good impression of themselves. While everyone agrees that social networking has had a significant impact on social interaction, there remains a substantial disagreement as to whether the nature of this impact is completely positive. A number of scholars have done research on the negative effects of Internet communication as well. These researchers have contended that this form of communication is an impoverished version of conventional face-to-face social interactions, and therefore produce negative outcomes such as loneliness and depression for users who rely on social networking entirely. By engaging solely in online communication, interactions between communities, families, and other social groups are weakened.

Issues

Main article: Issues relating to social networking services

Social networking services have led to many issues regarding privacy, bullying, social anxiety and potential for misuse.

Investigations

Main article: Use of social network websites in investigations

Social networking services are increasingly being used in legal and criminal investigations. Information posted on sites such as MySpace and Facebook has been used by police (forensic profiling), probation, and university officials to prosecute users of said sites. In some situations, content posted on MySpace has been used in court.

Facebook is increasingly being used by school administrations and law enforcement agencies as a source of evidence against student users. This site being the number one online destination for college students, allows users to create profile pages with personal details. These pages can be viewed by other registered users from the same school, which often include resident assistants and campus police who have signed up for the service. One UK police force has sifted pictures from Facebook and arrested some people who had been photographed in a public place holding a weapon such as a knife (having a weapon in a public place is illegal).

Application domains

Government applications

Banner in Bangkok, observed on June 30, 2014, during the 2014 Thai coup d'état, informing the Thai public that 'like' or 'share' activity on social media could land them in prison

Social networking is more recently being used by various government agencies. Social networking tools serve as a quick and easy way for the government to get the suggestion of the public and to keep the public updated on their activity, however this comes with a significant risk of abuse, for example, to cultivate a culture of fear such as that outlined in Nineteen Eighty-Four or THX-1138.

The Centers for Disease Control demonstrated the importance of vaccinations on the popular children's site Whyville and the National Oceanic and Atmospheric Administration has a virtual island on Second Life where people can explore caves or explore the effects of global warming. Likewise, NASA has taken advantage of a few social networking tools, including Twitter and Flickr. The NSA is taking advantage of them all. NASA is using such tools to aid the Review of U.S. Human Space Flight Plans Committee, whose goal it is to ensure that the nation is on a vigorous and sustainable path to achieving its boldest aspirations in space.

Business applications

The use of social networking services in an enterprise context presents the potential of having a major impact on the world of business and work. Social networks connect people at low cost; this can be beneficial for entrepreneurs and small businesses looking to expand their contact bases. These networks often act as a customer relationship management tool for companies selling products and services. Companies can also use social networks for advertising in the form of banners and text ads. Since businesses operate globally, social networks can make it easier to keep in touch with contacts around the world. Applications for social networking sites have extended toward businesses and brands are creating their own, high functioning sites, a sector known as brand networking. It is the idea that a brand can build its consumer relationship by connecting their consumers to the brand image on a platform that provides them relative content, elements of participation, and a ranking or score system. Brand networking is a new way to capitalize on social trends as a marketing tool. The power of social networks is beginning to permeate into internal culture of businesses where they are finding uses for collaboration, file sharing and knowledge transfer. The term "enterprise social software" is becoming increasingly popular for these types of applications.

Dating applications

See also: Online dating service

Many social networks provide an online environment for people to communicate and exchange personal information for dating purposes. Intentions can vary from looking for a one time date, short-term relationships, and long-term relationships. Most of these social networks, just like online dating services, require users to give out certain pieces of information. This usually includes a user's age, gender, location, interests, and perhaps a picture. Releasing very personal information is usually discouraged for safety reasons. This allows other users to search or be searched by some sort of criteria, but at the same time, people can maintain a degree of anonymity similar to most online dating services. Online dating sites are similar to social networks in the sense that users create profiles to meet and communicate with others, but their activities on such sites are for the sole purpose of finding a person of interest to date. Social networks do not necessarily have to be for dating; many users simply use it for keeping in touch with friends, and colleagues.

However, an important difference between social networks and online dating services is the fact that online dating sites usually require a fee, where social networks are free. This difference is one of the reasons the online dating industry is seeing a massive decrease in revenue due to many users opting to use social networking services instead. Many popular online dating services such as Match.com, Yahoo Personals, and eHarmony.com are seeing a decrease in users, where social networks like MySpace and Facebook are experiencing an increase in users. The number of Internet users in the United States that visit online dating sites has fallen from a peak of 21% in 2003 to 10% in 2006. Whether it is the cost of the services, the variety of users with different intentions, or any other reason, it is undeniable that social networking sites are quickly becoming the new way to find dates online.

Educational applications

The National School Boards Association reports that almost 60% of students who use social networking talk about education topics online, and more than 50% talk specifically about schoolwork. Yet the vast majority of school districts have stringent rules against nearly all forms of social networking during the school day—even though students and parents report few problem behaviors online. Social networks focused on supporting relationships between teachers and their students are now used for learning, educators professional development, and content sharing. HASTAC is a collaborative social network space for new modes of learning and research in higher education, K-12, and lifelong learning; Ning supports teachers; TermWiki, TeachStreet and other sites are being built to foster relationships that include educational blogs, portfolios, formal and ad hoc communities, as well as communication such as chats, discussion threads, and synchronous forums. These sites also have content sharing and rating features. Social networks are also emerging as online yearbooks, both public and private. One such service is MyYearbook, which allows anyone from the general public to register and connect. A new trend emerging is private label yearbooks accessible only by students, parents, and teachers of a particular school, similar to Facebook's beginning within Harvard.

Finance applications

The use of virtual currency systems inside social networks create new opportunities for global finance. Hub Culture operates a virtual currency Ven used for global transactions among members, product sales and financial trades in commodities and carbon credits. In May 2010, carbon pricing contracts were introduced to the weighted basket of currencies and commodities that determine the floating exchange value of Ven. The introduction of carbon to the calculation price of the currency made Ven the first and only currency that is linked to the environment.

Medical and health applications

Social networks are beginning to be adopted by healthcare professionals as a means to manage institutional knowledge, disseminate peer to peer knowledge and to highlight individual physicians and institutions. The advantage of using a dedicated medical social networking site is that all the members are screened against the state licensing board list of practitioners. A new trend is emerging with social networks created to help its members with various physical and mental ailments. For people suffering from life-altering diseases or chronic health conditions, companies such as HealthUnlocked and PatientsLikeMe offers their members the chance to connect with others dealing with similar issues and share experiences. For alcoholics and addicts, SoberCircle gives people in recovery the ability to communicate with one another and strengthen their recovery through the encouragement of others who can relate to their situation. DailyStrength is also a website that offers support groups for a wide array of topics and conditions, including the support topics offered by PatientsLikeMe and SoberCircle. Some social networks aim to encourage healthy lifestyles in their users. SparkPeople and HealthUnlocked offer community and social networking tools for peer support during weight loss. Fitocracy and QUENTIQ are focused on exercise, enabling users to share their own workouts and comment on those of other users. Other aspects of social network usage include the analysis of data coming from existing social networks (such as Twitter) to discover large crowd concentration events (based on tweets location statistical analysis) and disseminate the information to e.g. mobility-challenged individuals for e.g. avoiding the specific areas and optimizing their journey in an urban environment.

Social and political applications

Social networking sites have recently showed a value in social and political movements. In the Egyptian revolution, Facebook and Twitter both played an allegedly pivotal role in keeping people connected to the revolt. Egyptian activists have credited social networking sites with providing a platform for planning protest and sharing news from Tahrir Square in real time. By presenting a platform for thousands of people to instantaneously share videos of mainly events featuring brutality, social networking can be a vital tool in revolutions. On the flip side, social networks enable government authorities to easily identify, and repress, protestors and dissidents. Another thing that social media helps with in political applications is getting the younger generations involved in politics and ongoing political issues.

Perhaps the most significant political application of social media is Barack Obama's election campaign in 2008. It was the first of its kind, as it successfully incorporated social media into its campaign winning strategy, evolving the way of political campaigns forevermore in the ever-changing technological world we find ourselves in today. His campaign won by engaging everyday people and empowering volunteers, donors, and advocates, through social networks, text messaging, email messaging and online videos. Obama's social media campaign was vast, with his campaign boasting 5 million 'friends' on over 15 social networking sites, with over 3 million friends just on Facebook. Another significant success of the campaign was online videos, with nearly 2,000 YouTube videos being put online, receiving over 80 million views.

In 2007, when Obama first announced his candidacy, there was no such thing as an iPhone or Twitter. However, a year later, Obama was sending out voting reminders to thousands of people through Twitter, showing just how fast social media moves. Obama's campaign was current and needed to be successful in incorporating social media, as social media acts best and is most effective in real time.

Building up to the 2012 presidential election, it was interesting to see how strong the influence of social media would be following the 2008 campaigns, where Obama's winning campaign had been social media-heavy, whereas McCain's campaign did not really grasp social media. John F. Kennedy was the first president who really understood television, and similarly, Obama is the first president to fully understand the power of social media. Obama has recognized social media is about creating relationships and connections and therefore used social media to the advantage of presidential election campaigns, in which Obama has dominated his opponents in terms of social media space.

Other political campaigns have followed on from Obama's successful social media campaigns, recognizing the power of social media and incorporating it as a key factor embedded within their political campaigns, for example, Donald Trump's presidential electoral campaign, 2016. Dan Pfeiffer, Obama's former digital and social media guru, commented that Donald Trump is "way better at the internet than anyone else in the GOP which is partly why he is winning".

Research has shown that 66% of social media users actively engage in political activity online, and like many other behaviors, online activities translate into offline ones. With research from the 'MacArthur Research Network on Youth and Participatory Politics' stating that young people who are politically active online are double as likely to vote than those who are not politically active online. Therefore, political applications of social networking sites are crucial, particularly to engage with the youth, who perhaps are the least educated in politics and the most in social networking sites. Social media is, therefore, a very effective way in which politicians can connect with a younger audience through their political campaigns.

On June 28, 2020, The New York Times released an article sharing the finding of two researchers who studied the impact of TikTok, a video-sharing and social networking application, on political expression. The application, besides being a creative space to express oneself, has been used maliciously to spread disinformation ahead of US President Donald Trump's Tulsa rally in Oklahoma and amplified footage of police brutality at Black Lives Matter protests.

Crowdsourcing applications

Main article: Crowdsourcing creative work

Crowdsourcing social media platform, such as Design Contest, Arcbazar, Tongal, combined group of professional freelancers, such as designers, and help them communicate with business owners interested in their suggestion. This process is often used to subdivide tedious work or to fund-raise startup companies and charities, and can also occur offline.

Open source software

Main article: Comparison of software and protocols for distributed social networking

There are a number of projects that aim to develop free and open source software to use for social networking services. These technologies are often referred to as social engine or social networking engine software.

Largest social networking services

The following is a list of the largest social networking services, in order by number of active users, as of April 2021, as published by Statista:

Service	Active users (in millions)
Facebook	2,853
YouTube	2,291
WhatsApp*	2,000
Instagram	1,386
Facebook Messenger	1,300
WeChat	1,250
TikTok	1,000
QQ	606
Douyin**	600
Sina Weibo	566
Telegram	550
Kuaishou*	481
Twitter	478
Pinterest	478
Reddit*	430
Quora*	300
Snapchat	293

*Platforms have not published updated user figures in the past 12 months, figures may be out of date and less reliable
**Figure uses daily active users, so monthly active user number is likely higher