I tried to update my system to the latest -STABLE, but got -RC or -PRERELEASE! What is going on?
Short answer: it is just a name. RC stands for “Release Candidate”. It signifies that a release is imminent. In FreeBSD, -PRERELEASE is typically synonymous with the code freeze before a release. (For some releases, the -BETA label was used in the same way as -PRERELEASE.) Long answer: FreeBSD derives its releases from one of two places. Major, dot-zero, releases, such as 3.0-RELEASE and 4.0-RELEASE, are branched from the head of the development stream, commonly referred to as -CURRENT. Minor releases, such as 3.1-RELEASE or 4.2-RELEASE, have been snapshots of the active -STABLE branch. Starting with 4.3-RELEASE, each release also now has its own branch which can be tracked by people requiring an extremely conservative rate of development (typically only security advisories). When a release is about to be made, the branch from which it will be derived from has to undergo a certain process. Part of this process is a code freeze. When a code freeze is initiated, the name of the branch