Kernel versions and release cycle

In short: The kernel has version numbers like 6.12.5: major version, minor version, patch level. About every nine to ten weeks a new minor version appears, with bug fixes in between.

In more detail: The major version jumps when Linus Torvalds finds the minor version too high, usually after about 19 to 20: 3.19 → 4.0, 4.20 → 5.0, 5.19 → 6.0. After 6.19 came the 7.x series. The number says nothing about big changes.

In detail

• Mainline: Linus’s main branch. Each development cycle has a two-week merge window followed by release candidates (rc1 to rc7 or rc8).
• Stable: bug fixes for the current version (6.x.1, 6.x.2 …) until the next version.
• Longterm (LTS): selected versions receive fixes for several years, usually one per year, the last of the year. For example 5.10, 5.15, 6.1, 6.6, 6.12 and 6.18.
• Distribution kernels: Debian 12 uses 6.1, Debian 13 uses 6.12, Ubuntu 24.04 starts with 6.8 (later updatable via the hardware enablement stack).
• Names: 6.12.5-arch1-1, 6.8.0-45-generic: the suffix shows distribution and variant.
• Check current: kernel.org shows mainline, stable and longterm with end dates.
• Note: the exact number of currently maintained LTS versions keeps changing, so look it up there.

See also: The Linux kernel at a glance, Release models: fixed, LTS and rolling