پی (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 پی is approximately 3.14159, but it has been calculated to trillions of digits beyond the decimal point. پی is widely used in various fields of mathematics and science, particularly in geometry and trigonometry. It plays a crucial role in calculations involving circles, such as finding the area and circumference. The symbol for پی is derived from the Greek word for "perimeter," reflecting its connection to circular measurements.