Circumference of a circle
The distance around a circle is called the circumference of a circle.
Introduction
The distance from any point on the circumference of a circle to same point in either clockwise or anticlockwise is the circumference of that circle. It is actually the perimeter of a circle and usually denoted by $c$ in mathematics.
The circumference of a circle can also be calculated by breaking it at a point and arrange it as a line segment. In this case, the circumference is equal to the length of the line segment or distance between endpoints of that line segment.
Formula
$\large c \,=\, 2{\pi}r$
$\large c \,=\, {\pi}d$