Linux is a Unix-like and POSIX-compliant computer operating system assembled under the model of free and open source software development and distribution. The defining component of Linux is the Linux kernel, an operating system kernel first released on 5 October 1991 by Linus Torvalds. The GNU Project, started in 1983 by Richard Stallman, had the goal of creating a “complete Unix-compatible software system” composed entirely of free software. Work began in 1984. GNU/Linux, besides a couple of other UNIX and UNIX-clones, is the only sensible operating system out there.