Tree
From Interaction-Patterns.org
Resources found while doing a google search: http://www.cs.helsinki.fi/u/salaakso/patterns/Tree.html
Tree is a visualization of a hierarchy. In the most typical orthogonal 2D layout of the Tree, the hierarchy level is shown by indentation on the left side of the Tree nodes.
Most Trees are used as overviews for more detailed data in an Overview beside Detail structure.

