Have a look at:
- Subversion
- Git
- Mercurial
- Perforce (free for Open Source projects or non-Enterprise users)
The technology you're looking for is called Source Control. A repository is a term used by most of the different source control tools to refer to the collection of source code. A source control instance (such as SVN) can have many repositories. Usually a repository contains a project, or a group of projects that are closely related. Distinct projects would be a good example where you'd want to make use of multiple repositories.
Git and Mercurial are distributed source controls tools, whereas SVN and Perforce are not.
A few providers offer IDE integrations (Perforce offers one, you can get ones for Subversion, ie: Ankh for Visual Studio). Other users opt to deal with source control outside the IDE as a purely file system options.
If you're happy to have your source code in the cloud, git hub might be a good solution. They offer free Git repositories that you don't need to manage.
