Card sorting is a research method used by UX and user researchers to uncover users’ mental models and better understand how people naturally categorize information. It involves having study participants group information by sorting cards into categories. 

There are three types of card sorting exercises:

Open — Users sort cards into groups, and then name the groups

Closed — Users sort cards into an existing set of categories 

Hybrid — Same as closed, except users can also create new categories

Moderated card sorts

• Typically done in-person
• Usually more expensive and time-consuming
• Requires more coordination
• Allows for user “narration” of sorting choices to provide additional visibility into thought process
• Provides the option for a debrief in which to ask follow-up questions and capture qualitative insights
• Requires additional time and resources for data analysis

Unmoderated card sorts

• Usually done remotely via an online tool
• Tends to be faster and less expensive
• Fairly easy to organize
• May provide shallower qualitative insights
• Often used as a complement to moderated sessions