How Linux Kernels Are Numbered.

There are three different Linux kernel numbering systems. The very first Linux kernel version was 0.01, followed by 0.02 through 0.03, then 0.10 through 0.12, and then 0.95 through 1.0 and onward to the current version. That was the first kernel version numbering scheme. From Linux release 1.0 through to just before release 2.6, the kernel version numbering system was composed of three numbers, each separated by a decimal point. The first number was the kernel version, with the second number being a major revision of that kernel version, and the third number being for minor revisions (such as for bug fixes and security patches). As of 2004, the kernel version numbering system has undergone a third change in which the version consists of 3 to 4 numbers, each separated by a decimal, with the third number being the actual kernel version number. The fourth number now indicating security patches and/or bug fixes. A kernel version with the letters "rc" in front of the numbers indicates a release candidate version. Letters after the numbers may indicate initials representing who made that kernel version, or may instead be initials or an abbreviation that indicate what that particular kernel release is meant for.