GrandPerspective visualises disk usage using so-called tree maps. A view window shows the contents of a given folder. Each rectangle in the view window represents a file in the folder. The area of the rectangle is proportional to the file's size. Files in the same folder appear together, but their placement is otherwise arbitrary. You can focus on a file by hovering the mouse pointer over it. The name of the file, together with its size, is then shown at the bottom of the view window.
A view where each file is colored by Folder. Indicated are: 1) a small file, 2) a large file, and 3) a folder.
