A circle is a simple shape of Euclidean geometry that is the set of all points in a plane that are at a given distance from a given point, the centre. The distance between any of the points and the centre is called the radius. It can also be defined as the locus of a point equidistant from a fixed point.This description offers a mathematical explanation of what constitutes a circle. But when does a circle become a circle by other criteria, and when does a circle stop being a circle? If I walk around in a circle without leaving any trace, is a circle still created? Or is it only considered a circle if there is visual evidence of said walking around in a circle? Is a circle just an abstract concept created to better understand the complexity of nature or does a circle have an actual physical presence?