All modern clocks require four basic components. First, it requires a source of power, either mechanically or electronically. Second, it needs a sort of time base that will give the clock rhythm. Third, it requires a sort of gear system that will allow it different components of time (seconds, minutes, hours). Finally, a clock needs a way to actually display the time.
Revolutionized by the Dutch astronomer Christiaan Huygens in 1656, pendulum clocks were the first clock designed that maintained its accuracy. Several noticeable parts of the pendulum clock are the face of the clock, with its hour and minute hand, one or more weights, and the pendulum itself. Pendulums swing once per second in wall clocks, but it might swing up to twice per second in small cuckoo clocks, and in large grandfather clocks, the pendulum swings once every two seconds. The number of swings in the pendulum clock correlates with the lengths. The weight of the pendulum basically acts as an energy storage device, using potential energy as the weight swings back and forth while runn