Concept mapping is a technique for representing knowledge in graphs. Knowledge graphs are networks of concepts. Networks consist of nodes (points/vertices) and links (arcs/edges). Nodes represent concepts and links represent the relations between concepts.
Concepts, and sometimes links, are labeled. Links can be non-, uni- or bi-directional. Concepts and links may be categorized, they can be simply associative, specified or divided in categories such as causal or temporal relations.
Concept mapping can be done for for several purposes:
The above is intentionally out of date as a memorial to its author. DMOZ (see OpenDirectoryProject) has a category, though:http://www.luca.demon.co.uk/TheoryOfObjects/ConceptMap.html from TheoryOfObjects
For a really excellent example of a tool aimed at creating concept maps, cf. http://cmap.ihmc.us/ (W32/Linux/Solaris; freeware); it is still being developed and is updated regularly. With the Easy-Mapping-Tool you can draw maps online, you only need a browser (basic online version is free, advanced version is commercial, (UNIX/Linux/Windows/MacOsx): http://www.cognitive-tools.com - online available mapping-software for learning and thinking
A random visitor claimed: "The premier concept mapping tool used in K-12 education is Inspiration by Inspiration Software: http://inspiration.com/productinfo/inspiration/index.cfm" Unless "Inspiration" really does occupy a leading role in the North American K-12 education field, I suggest this paragraph be deleted as it sounds like blatant advertising.