Debian (/ ˈ d ɛ b i ə n /), also known as Debian GNU/Linux, is a GNU/Linux distribution composed of free and open-source software, developed by the community-supported Debian Project, which was established by Ian Murdock on August 16, 1993. The first version of Debian (0.01) was released on September 15, 1993, and its first stable version (1.1) was released on June 17, 1996.

At any given time, there is one stable release of Debian, which has the support of the Debian security team. When a new stable version is released, the security team will usually cover the previous version for a year or so, while they also cover the new/current version. Only stable is recommended for production use.