A mental model is the explanation users have of how a system works or how they think it works. Ideally, users' mental models should be close to reality, as they make predictions and adjust their behavior based on their beliefs. According to Jakob's Law of Internet User Experience, users spend most of their time on other sites, which means they expect yours to work similarly.^[1] When a website's navigation is too different from what people expect, they feel confused and may abandon the site out of disappointment.

Another dilemma is that each individual has a different mental model, and designers are no exception. Their mindset of how things should be in a system can radically contradict users' standpoints. Thus, a designer's prime goal is to create intuitive and valuable interfaces that meet users' expectations.

The card sorting method is a tool that indicates the gaps between designers' and users' mental models. Based on how users group items, designers can make conclusions about users' thinking and build intuitive information architecture that users understand at a glimpse.