The TreeMap is a constant area visualisation invented by Ben Shneiderman for hierarchical data with some form of numerical attribute, for example the sizes of files and folders on a computer disk. The most basic form starts with a rectangular area and then recursively divides the area alternatively horizontally using the total values for each level.

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### Links:

- cs.umd.edu: Treemaps for space-constrained visualization of hierarchies
- Wikipedia: Treemapping