Glossary
Card sorting
What is Card Sorting?
Card sorting is a user research method where participants organize topics written on cards into groups that make sense to them, revealing how users mentally categorize information.
How it works
- In an open card sort, participants create their own category names, revealing natural mental models.
- In a closed card sort, categories are predefined and participants place cards into them, testing whether an existing structure matches user expectations.
- Hybrid sorts allow both.
Card sorting is most commonly used to design information architecture, navigation menus, and content organization. Results are analyzed using dendrograms (similarity trees) and similarity matrices to identify clusters of items that users consistently group together.
Applied example
Imagine a healthcare site asking patients to group medical topics. Patients might put “headache” and “fatigue” under symptoms rather than use departments such as neurology and endocrinology. The team can use those groups to draft navigation, then test whether people can find what they need.
Why it matters
Card sorting helps expose the gap between an organization’s internal categories and the way users group information. It gives a team candidate structures to test; it does not by itself show that people can follow the finished navigation or understand every label. Tree testing can answer that next question by asking people to find items in a text-only version of the proposed structure.
Card sorting versus affinity mapping
Both methods put items into groups, but they answer different questions. In card sorting, researchers prepare the items and study how participants organize them. In affinity mapping, a team usually groups observations, notes, or ideas generated during research. One investigates users’ categories; the other helps a team make sense of its own evidence.