원주율, or pi, is a mathematical constant that represents the ratio of a circle's circumference to its diameter. It is an irrational number, meaning it cannot be expressed as a simple fraction, and its decimal representation goes on forever without repeating. The value of 원주율 is approximately 3.14, but it has been calculated to trillions of digits. 원주율 is widely used in various fields, including mathematics, engineering, and physics. It plays a crucial role in calculations involving circles, such as determining the area and circumference. Understanding 원주율 is essential for anyone studying geometry or related disciplines.