Debian releases do not follow a fixed schedule. Recent releases have been made roughly biennially by the Debian Project. The most recent version of Debian is Debian version 11, codename "Bullseye". The next up and coming release of Debian is Debian 12 codename "Bookworm". When the Debian stable branch is replaced with a newer release, the current stable becomes an "oldstable" release. When the Debian stable branch is replaced again, the oldstable release becomes the "oldoldstable" release. Oldoldstable is eventually moved to the archived releases repository.