Debian GNU/Linux is one of the oldest distributions (first release was 1993) and currently the largest distribution not backed by any company. Additionally, it is a common starting point for new distributions. Debian is known for its lengthly release circles (one new version every couple of years) and most users that depend on the stable set of repositories use outdated software (with only security patches backported). Fortunately, many users prefer to use the unstable set since the stable one is mostly oriented towards servers and other environments where security and stability is more important than having the latest and greatest features.

Ubuntu and Linux Mint are popular distributions based on Debian.