That's your computer. Easy to figure out what that's for. Also think People, and Favorites. Think Cocoa APIs. Think Apache built in.
Applications are there.
This niftly little guy allows three different views types. The first is the traditional way we know of now with icons or in a list view. The second view is a new one for Mac called tree view. It works in branches from left to right in three panels. The third view is the coolest.