Linux kernel

"This article is about the kernel. For the Operating System, see Linux."The Linux kernel is an open source monolithic Unix-like computer 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. The Androidoperating system for tablet computers, smartphones, and smartwatches uses services provided by the Linux kernel to implement its functionality. While the adoption on desktop computers 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.[10]

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.[12] The Linux kernel has received contributions from nearly 12,000 programmers from more than 1,200 companies, including some of the largest software and hardware vendors.

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, and it's supported up to six years depending on version. 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.