What is Pi (π) - Definition, Value, and Uses

Pi (π) is a mathematical constant that represents the ratio of the circumference of a circle to its diameter. It's an irrational number, which means it cannot be expressed as a finite decimal or a fraction. The value of pi is approximately 3.14159, but it goes on infinitely without repeating. Pi is used in many calculations involving circles, such as finding the area and circumference of a circle.