Water clocks, also known as clepsydras, are ancient timekeeping devices that measure time by the flow of water. They typically consist of a container that holds water, which drips or flows at a consistent rate. As the water level decreases, markings on the container indicate the passage of time. These clocks were used by various civilizations, including the Egyptians and Greeks, to track time for daily activities and events. While not as precise as modern clocks, water clocks were innovative for their time and laid the groundwork for future timekeeping methods.