A 시계 (clock) is a device used to measure and display time. It typically consists of a face with numbers and hands that move to indicate the hours and minutes. Clocks can be found in various forms, including wall clocks, wristwatches, and digital displays. Clocks operate using different mechanisms, such as mechanical gears or electronic circuits. They can also feature additional functions, like alarms and timers. The invention of the clock has greatly influenced daily life, helping people organize their schedules and activities more efficiently.