Tags
Revision numbers are unique to each file in CVS. This means that files that are updated a lot will have much higher revision numbers than stable files. In order to be able to call up all of the files that were current at a certain point in time (when version 2.0 of WonderSoft was released for example), you can issue a tag comment and all current files will be marked that the tag. Later you can retrieve the entire group of files using this tag.