In mechanical watches and clocks, a device which converts continuous rotational motion into an oscillating or back and forth motion or a mechanism that permits motion in only one direction, allowing power from a coiled spring or falling weight to turn gears connected to the hands.

Without the escapement, the system would simply unwind uncontrollably, but the escapement regulates this motion, controlled by the periodic swing of the pendulum or balance wheel.

It allows the gears to advance or "to escape" a fixed amount with each swing, moving the timepiece's hands forward at a steady rate.

A second function of the escapement is to keep the pendulum or balance wheel moving by giving it small pushes.