Branching and Tagging are cheap

Branching in CVS is painful. In fact you probably won't use branching until you happen to make a mistake in the commands and end up creating a branch. Branching is quite useful in larger projects. The idea of a branch is that you can work on a feature of a big program without affecting the main line of work. Once you have the new feature working you can merge it back onto the main branch and give it to the world.