Mental models relate to the field of cognitive psychology. Mental models consist of mental units created of a system existing in the real world (the process of reading on the paper, the process of shopping in the grocery) including the phenomenon and its connections. Mental models help to implement everyday tasks to online interfaces (reading an e-book reader, online shopping) in a way that will suit the way of thinking and expectations of the users.

To visualize thproperly weline properly we must be familiar with how users think about the process, to which steps they break it down and which notions they use. Where, what and why they emphasize certain instances? The answers are essential in order to build an interface based on the user’s mental models instead of the mental model of the owner or the designer.