[Debian][1] is a Unix-like computer operating system that is composed entirely of free software and packaged by a group of individuals participating in the Debian Project.  

Debian runs on a wide variety of hardware.  Several popular Linux distributions like Ubuntu, Mepis, Raspbian, SteamOS, *et al* are [based on Debian][2].


  [1]: https://en.wikipedia.org/wiki/Debian
  [2]: https://en.wikipedia.org/wiki/List_of_Linux_distributions#Debian-based