A
mind map is a diagram used to represent word, ideas, tasks, or other items linked to and arranged around a central key word or idea. Mind maps are used to general, visualize, structure, and classify ideas, and as an aid to studying and organizing information, solving problem, making decisions, and writing.
By presenting ideas in a radial, graphical, non-linear manner, mind maps encourage a brainstorm, approach to planning and organizational tasks. Though the branches of a mindmap represent hierarchical tree structures, their radial arrangement disrupts the prioritizing of concepts typically associated with hierarchies presented with more linear visual cues. This orientation towards brainstorming encourages users to enumerate and connect concepts without a tendency to begin within a particular conceptual framework.
Source
http://en.wikipedia.org/wiki/Mind_map