Interaction design laws
Jakob's law
People spend most of their time on other sites and apps, so they expect yours to work the same way as the ones they already know.
Conventions are learned elsewhere: the logo links home, the cart is top right, swiping left on a message reveals actions. Following them lets people use your product without learning it.
Be original where it adds real value, and conventional everywhere else. When you must change something familiar, give people time to adjust.
In practice
An online shop that puts search at the top and the basket in the top right corner, where shoppers look for them.
Common mistake
Reinventing standard controls to look distinctive, so people have to learn a menu or a checkout all over again.
Where it comes from
Set out by usability expert Jakob Nielsen in 2000.