SVN is a release management system documented at http://subversion.tigris.org/
Let me be very clear: SVN is NOT a real configuration management system, though it is often called that. Instead, SVN is a release management system.
There is nothing wrong with that, but if you are used to any of the following real configuration management systems, you need to be extremely careful about imagining what SVN is:
SVN gives "some" slight improvement over CVS -- particularly in the area of network accessibility. But SVN also takes away many important features -- such as proper branches and proper diffing of deleted branches against one another.
SVN is it's own thing and can be used effectively, but it may not be the most advisable choice of CM systems for an organization that needs to have large numbers branches under current development.
It's principle limitation is that it is extremely difficult to compare files in deleted branches to other files (deleted or not). It's merge tool is broken and pathetic, but you can make it work if you try hard enough.
1.6.3