Jakob's Law
Users spend most of their time on other sites. This means that users prefer your site to work the same way as all the other sites they already know.
Key Takeaways
Users transfer expectations they have built around one familiar product to another that appears similar.
By leveraging existing mental models, designers can create superior user experiences where users focus on their tasks rather than learning new interaction patterns.
When making changes, minimize discord by empowering users to continue using a familiar version for a limited time during transitions.
Origin
Jakob's Law was articulated by Jakob Nielsen, a User Advocate and principal of the Nielsen Norman Group, which he co-founded with Dr. Donald A. Norman (former VP of research at Apple Computer). Nielsen pioneered the "discount usability engineering" movement for fast and cheap improvements of user interfaces and invented several usability methods, including heuristic evaluation. His law reflects decades of observation that users build up expectations from the cumulative experience of using other websites and applications.