시 (Time) is a fundamental concept that helps us understand the sequence and duration of events. It is measured in units such as seconds, minutes, hours, days, and years. Time allows us to organize our lives, schedule activities, and plan for the future. In physics, time is often considered a dimension, similar to space. It plays a crucial role in various scientific theories, including Einstein's theory of relativity, which explores how time can be affected by speed and gravity. Understanding time is essential for fields like astronomy, history, and philosophy, as it influences how we perceive change and existence.