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
A healthcare website asks 30 patients to sort 50 medical topics into groups. Results reveal that patients group by symptom (headache, fatigue) rather than by medical specialty (neurology, endocrinology), leading the team to restructure navigation around patient concerns rather than clinical departments.
Why it matters
Card sorting grounds information architecture in actual user mental models rather than organizational assumptions, preventing the common mistake of structuring content around internal categories that users don’t understand.
