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Linux kernel
Tux
Tux the penguin, mascot of Linux
Linux 3.0.0 boot.png
Linux kernel 3.0.0 booting
DeveloperLinus Torvalds and thousands of collaborators
Written inC and assembly
OS familyUnix-like
Initial release0.01 (17 September 1991
Latest release5.0.9 (20 April 2019)
Latest preview5.1-rc6 (21 April 2019)
Available inEnglish
Kernel typeMonolithic
LicenseGPLv2 with optional binary blobs
Official websitekernel.org

The Linux kernel is a free and open-source, monolithic, Unix-like operating system kernel. The Linux family of operating systems is based on this kernel and deployed on both traditional computer systems such as personal computers and servers, usually in the form of Linux distributions, and on various embedded devices such as routers, wireless access points, PBXes, set-top boxes, FTA receivers, smart TVs, PVRs, and NAS appliances. While the adoption of the Linux kernel in desktop computer operating system is low, Linux-based operating systems dominate nearly every other segment of computing, from mobile devices to mainframes. As of November 2017, all of the world's 500 most powerful supercomputers run Linux. The Android operating system for tablet computers, smartphones, and smartwatches also uses the Linux kernel.

The Linux kernel was conceived and created in 1991 by Linus Torvalds for his personal computer and with no cross-platform intentions, but has since expanded to support a huge array of computer architectures, many more than other operating systems or kernels. Linux rapidly attracted developers and users who adopted it as the kernel for other free software projects, notably the GNU Operating System, which was created as a free, non-proprietary operating system, and based on UNIX as a by-product of the fallout of the Unix wars.

The Linux kernel API, the application programming interface (API) through which user programs interact with the kernel, is meant to be very stable and to not break userspace programs (some programs, such as those with GUIs, rely on other APIs as well). As part of the kernel's functionality, device drivers control the hardware; "mainlined" device drivers are also meant to be very stable. However, the interface between the kernel and loadable kernel modules (LKMs), unlike in many other kernels and operating systems, is not meant to be very stable by design.

The Linux kernel, developed by contributors worldwide, is a prominent example of free and open source software. Day-to-day development discussions take place on the Linux kernel mailing list (LKML). The Linux kernel is released under the GNU General Public License version 2 (GPLv2), with some firmware images released under various non-free licenses.

History