Web Design Glossary...
Affinity Diagram
Affinity diagramming is a categorization method where users sort various concepts into several categories. This usability method is used by a team to organize a large amount of data according to the natural relationships between the items. Basically, you write each concept on a Post-It note and tack them onto a wall. Team members move the notes to groups based on how they feel the concept belongs with other concepts. For more information visit: Affinity Diagrams.