Card sorting

Card sorting is a research method in which participants sort cards — each naming a piece of content — into groups that make sense to them. It reveals users' Mental models and vocabulary before a structure is fixed.

Variants

• Open card sort — participants create and name their own groups. Best for discovering categories and labels.
• Closed card sort — participants sort cards into predefined categories. Best for checking whether existing categories work.
• Hybrid — predefined categories, but participants may add their own.

Running one

1. Pick 30–60 representative content items; write them in the users' language, not internal jargon
2. Recruit participants from each important user group (15–30 per group is common for remote sorts)
3. Analyze agreement: similarity matrices and dendrograms show which items people group together
4. Read the group names participants chose — raw material for Labeling systems

What it doesn't tell you

Card sorting shows how people group things, not whether they can find them in a hierarchy. For that, follow up with Tree testing. The results inform a Taxonomy and the top levels of Navigation systems.