One of the most helpful yet underused facilities of CVS is the
tag.
CVS's tagging feature allows you to label a revision
for later retrieval. This feature also allows you to fork development
so that you can work on two or more versions of your project
simultaneously. The version that has been forked off is called a
branch,
and the main line of development is called the
trunk.
This chapter explains tags, branches, and how to merge branches and
trunks. It also discusses why and when to branch and provides
strategies and hints for using branches effectively in your project.