4.6.5. Release code names

Every released Debian distribution has a code name: Debian 8 is called jessie; Debian 9, stretch; Debian 10, buster; the next release, Debian 11, will be called bullseye and Debian 12 will be called bookworm. There is also a pseudo-distribution, called sid, which is the current unstable distribution; since packages are moved from unstable to testing as they approach stability, sid itself is never released. As well as the usual contents of a Debian distribution, sid contains packages for architectures which are not yet officially supported or released by Debian. These architectures are planned to be integrated into the mainstream distribution at some future date. The codenames and versions for older releases are listed on the website.

Since Debian has an open development model (i.e., everyone can participate and follow the development) even the unstable and testing distributions are distributed to the Internet through the Debian FTP and HTTP server network. Thus, if we had called the directory which contains the release candidate version testing, then we would have to rename it to stable when the version is released, which would cause all FTP mirrors to re-retrieve the whole distribution (which is quite large).

On the other hand, if we called the distribution directories Debian-x.y from the beginning, people would think that Debian release x.y is available. (This happened in the past, where a CD-ROM vendor built a Debian 1.0 CD-ROM based on a pre-1.0 development version. That’s the reason why the first official Debian release was 1.1, and not 1.0.)

Thus, the names of the distribution directories in the archive are determined by their code names and not their release status (e.g., buster). These names stay the same during the development period and after the release; symbolic links, which can be changed easily, indicate the currently released stable distribution. That’s why the real distribution directories use the code names, while symbolic links for stable, testing, and unstable point to the appropriate release directories.