Miniature snap-action switch

A miniature snap-action switch, also trademarked and frequently known as a micro switch or microswitch, is an electric switch that is actuated by very little physical force, through the use of a tipping-point mechanism, sometimes called an "over-center" mechanism. The defining feature of micro switches is that a relatively small movement at the actuator button produces a relatively large movement at the electrical contacts, which occurs at high speed (regardless of the speed of actuation).

Source: Wikipedia — Miniature snap-action switch (CC BY-SA 4.0)