\pi
The symbol "\pi" represents a mathematical constant that is approximately equal to 3.14. It is defined as the ratio of a circle's circumference to its diameter, meaning that for any circle, if you divide the distance around the circle by the distance across it, you will always get \pi. This property makes \pi essential in geometry and trigonometry.
\pi is an irrational number, which means it cannot be expressed as a simple fraction and its decimal representation goes on forever without repeating. It has been calculated to trillions of digits, but for most practical purposes, using 3.14 or 22/7 is sufficient. The study of \pi has fascinated mathematicians for centuries, leading to various formulas and approximations.