The Linux kernel is an operating system kernel used by the Linux family of Unix-like operating systems. It is one of the most prominent examples of free and open source software.
The Linux kernel is released under the GNU General Public License version 2 (GPLv2) (plus some firmware images with various non-free licenses), and is developed by contributors worldwide. Day-to-day development takes place on the Linux kernel mailing list.
The Linux kernel was initially conceived and created by Finnish computer science student Linus Torvalds in 1991. Linux rapidly accumulated developers and users who adapted code from other free software projects for use with the new operating system. The Linux kernel has received contributions from thousands of programmers. Many Linux distributions have been released based upon the Linux kernel.