SVN?

[gdub33]

What exactly is it? I downloaded some files and some other program to use them because I want to see what the new version is looking like but I don't know the first thing about it. Is it a code for programming? I'm taking that next semester so I don't know anything about it yet. And is it hard to input the SVN code or w/e it is? And how would I go about doing that? Thanks for any help.