A pendulum escapement is a mechanism used in clocks to regulate timekeeping. It consists of a swinging pendulum that controls the release of energy from a gear train. As the pendulum swings back and forth, it allows the clock's gears to advance at a consistent rate, ensuring accurate time measurement. This invention was popularized by Christiaan Huygens in the 17th century, significantly improving the precision of clocks. The regular motion of the pendulum, combined with the escapement's design, creates a reliable timing system that has influenced many timekeeping devices throughout history, including modern mechanical clocks.