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.
Users will transfer expectations they have built around one familiar product to another that appears similar.
By leveraging existing mental models, we can create superior user experiences in which the user can focus on their task rather than learning new models.
Minimize discordance by empowering users to continue using a familiar version for a limited time.
Jakob’s Law was coined 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). Dr. Nielsen established the ‘discount usability engineering’ movement for fast and cheap improvements of user interfaces and has invented several usability methods, including heuristic evaluation.