What is all this blender branch ?

I see this tomato, pepper & onion branches in http://graphicall.org/blender, what are they ? please explain.

http://code.blender.org/index.php/2011/06/google-summer-of-code-salad/

A “branch” is a variation of blender, where new features are developed in. When the feature is complete, the branch is merged into trunk.

Those branches that are names of salad ingredients are from Google’s Summer of Code (GSOC). Here are eight videos explaining each of the salad branches. http://code.blender.org/index.php/2011/07/google-summer-of-code-midterm-videos/