The circumference of a circle is the distance around the circle. It is calculated as the product of the diameter of the circle and the mathematical constant pi (π). The formula for the circumference of a circle is C = πd, where C is the circumference, d is the diameter of the circle, and π is approximately equal to 3.14159.

The circumference of a circle is an important measurement in many real-world applications, including engineering, construction, and science. For example, it is used to calculate the length of materials needed for circular structures like pipes, cables, and conveyor belts. It is also used in calculating the distance traveled by a wheel or any circular object in one revolution. The concept of circumference is also important in geometry, as it is used to calculate the perimeter of circular shapes, such as circles, rings, and arcs.

The formula for determining the perimeter/circumference of a circle is defined as: