What are the three types of card sorting and what insight does each provide?

1. Open card sort: Participants group cards and name the groups themselves. Used in the discovery phase to understand users' mental models of how content should be organised. Ideal for designing new navigation or information architecture from scratch.
2. Closed card sort: Groups are pre-defined; participants place cards into existing categories. Used to validate a proposed structure or test whether items belong in expected categories. Useful when redesigning an existing navigation without changing the top-level structure.
3. Hybrid card sort: Participants can place cards into existing categories or create new ones. Balances discovery and validation — surfaces unexpected groupings while also testing the proposed structure. In Salesforce, card sorting informs App navigation, the order of page sections, and how to label Related Lists or Lightning App pages.