Card sorting is a research method that is helpful to upgrade your information architecture. The main principle here is that the participants have to group the cards with certain labels in the way it makes sense to them. So you can create an interface architecture that matches all the users’ expectations.
Paper and Digital.
Open and Closed. Open card sorting is the most common one: users are free to name the groups however they want. Closed card sorting, on the contrary, is provided with predetermined category names. Closed research method doesn’t provide the insight on how participants would naturally group the topics and can be used when you need to check if the users understand the already existing structure of the website.
Moderated and Unmoderated. Moderated card sorting includes the briefing of participants and communication all across the research. Users can be asked some questions to understand their behavior and give you some insights you are not able to receive without moderation. Unmoderated research leaves users to organize the content on their own and this makes it a faster and cheaper solution than the moderated card sorting.
Choose a set of topics.
Let the user organize selected topics into groups.
Let the user give the name to each group.
For moderated research: debrief the user. You may ask participants to explain how they organized the cards.