When UX practitioners discuss the card sorting method, they generally imply an open approach. In an open card sort, users group items and then create names for groups they've made by themselves.

Using an open card sort, you can:

• Learn users' mental models
• Understand how they search for information on a website
• Build new information architecture in a way users expect

Open card sorts are notably helpful for evaluating how multiple user groups perceive your content structure and find information. In a closed card sort, the category names are already predefined by researchers, and users are asked to sort cards out between these categories.

A closed card sort allows you to:

• Evaluate the effectiveness of the existing labeling system
• Identify which categories are excessive, unclear, or misleading
• Rank and prioritize categories. For example, you can ask users to distribute menu actions on an email app (e.g., Reply, Forward, Archive, Delete, Mark as Read, Move to, etc.) in groups such as “Mandatory,” “Optional,” “Frequently used,” and “I never use it.”