Debian is a Unix-like computer operating system that is composed entirely of free software, most of which is under the GNU General Public License and packaged by a group of individuals participating in the Debian Project. The Debian stable release branch is one of the most popular for personal computers and network servers, and has been used as a base for several other distributions. Debian comes with over 43000 packages, precompiled software bundled up in a nice format for easy installation on your machine.