Invented in the late 1800's, an escapement is a mechanical device that transfers the energy from a wound clock (an oscillating device) to the timekeeping element. The timekeeping elements were often pendulums like in a grandfather clock or Big Ben in London. Timekeeping elements may also be springs and vibrating quartz crystals found in most watches today. The escapement's force comes from a coiled spring or a suspended weight and transferred through a drive train. The "tick" you hear with a mechanical watch or clock is the action of the escapement releasing and then locking.
Historically, escapements provided for the invention of all-mechanical clocks and all efforts to "track time". The Flying Pendulum clock was invented in 1883 by Adler Christian Clausen and J. C. Slafter. The clock was later renamed the Ignatz Flying pendulum clock after a character in the Krazy Kat comic.
Watch the video and note how the timing of the escapement "regulates" the release.