Affinity Diagrams are a tool used to organize and present large amounts of data (such as ideas, issues, solutions, problems) into sets of logical categories based on their perceived relationships.

Affinity Diagrams are often created using "sticky notes" as part of brainstorming sessions, and grouped together by facilitator and participates. The final diagram shows relationships between the concepts being analyzed into the categories. These categories are ranked in terms of relative priorities. Duplicate issues are also combined to provide a simpler overview.