Card sorting is a user experience research technique used to help understand how users categorize information. It involves giving users cards with items printed on them, and asking them to place the cards into groups that make sense to them. This process helps you understand how your users think about and organize information, in other words their mental models.

Card sorting is extremely useful to the field of information architecture. With card sorting you can help create a standardized taxonomy that users of your system will better understand.

Steps in a Card Sort

1. Determine the learning objectives of the study.
2. Determine card sort type: Open card sorting, closed card sorting or hybrid card sorting. In an open card sort, users organize the cards into groups and give each group a name. In a closed card sort, you provide categories that are already named to the user as well as blank categories for them to add their own. In a hybrid card sort, you provide both open and closed card sorts to the user.
3. Choose the content for research participants to group. Place the key concepts from the content on cards (paper or digital). 4.Recruit, filter, and invite participants that represent who you want to understand better.
4. Run the card sort session(s) with the participants and record the results. Sessions can be with individuals or with focus groups. You can use cards/sticky notes if in person, or use an online tool.
5. Participants group the terms in whatever way they think is logical, and gives each group a category name, either from an existing card or by writing a name on a blank card.
6. Analyze the outcomes. You can generate a dendrogram or folksonomy to help.
7. Summarize insights for your projects.

Types of Card Sorts

Open Card Sort

Participants in an open card sort create their own names for the categories, they reveal not only how they mentally classify your topics but also what terms come to mind when thinking about that particular topic. Open sorting is generative - it helps reveal patterns and trends which then can be used as inspiration or input into other organizing systems.

Closed Card Sort

A technique that is used to evaluate existing organization of content. This process provides participants with predetermined categories and then they assign index cards accordingly, which reveals how many people agree on each category in order for it to become an effective way organize your collection of information.

Reverse Card Sort (Tree Test)

Tests existing structures of categories and sub-categories. It is good for testing existing navigation structures and information architectures (IA). Tree tests can isolate the IA from visual influences like color, menus, or distracting/attracting graphics. Reverse card sorting is evaluative as well.

Modified-Delphi Card Sort

Based on the (Delphi Method)[https://en.wikipedia.org/wiki/Delphi_method], this method has the first participant be the only one to do a full card sort. Each following participant uses the previous participant's model. Each iteration refines the card sort and builds consensus.