Snap action, or limit switches, are electromechanical devices that detect the presence or absence of an object or the position of a mechanism. They operate using a spring-loaded mechanism that rapidly snaps the contacts into position when triggered by a change in the object's position or pressure. Limit switches are commonly used in machinery, robotics, and industrial automation systems to control motion, position, and safety functions. They offer precise and reliable detection capabilities, making them essential components in modern manufacturing and assembly processes.