Principle of least astonishment

In user interface design and software design, the principle of least astonishment (POLA), also known as principle of least surprise (POLS), proposes that a component of a system should behave in a way that most users will expect it to behave, and therefore not astonish or surprise users. The following is a corollary of the principle: "If a necessary feature has a high astonishment factor, it may be necessary to redesign the feature." The principle has been in use in relation to computer interaction since at least the 1970s.

Source: Wikipedia — Principle of least astonishment (CC BY-SA 4.0)