You can now start to understand one of the biggest benefits of treemaps: you can see the whole disk hierarchy at once. Instead of having to click on a folder to see its contents, or having to drop down a plus-sign or an arrow on a tree to see its contents, all of its contents are immediately visible. And their contents are too. In fact, every file and folder on your C: drive is visible right now (assuming that this walk-through window doesn't cover them up!). Neat, huh?
Now that you understand the basic principle, let's look at the tools that SpaceMonger gives you to manage all this information.