The instrument used to measure time is called a clock. Clocks can be mechanical or digital, with mechanical clocks utilizing gears and pendulums to keep time, while digital clocks use electronic components. Clocks come in various forms, including wall clocks, wristwatches, and even timers. They are fundamental in daily life, helping people manage schedules, appointments, and activities. In addition to traditional clocks, there are also sundials and hourglasses, which represent some of the earliest methods of timekeeping. Overall, clocks play an essential role in organizing human activities within a 24-hour cycle.