One interesting fact regarding the circle is that, technically speaking, "circle" refers only to the edge of the shape. When referring to the whole shape, including the space inside, the term "disk" is used.
Another lesser-known fact about the circle is that when compared to other shapes with the same area, it has the shortest perimeter, which is the length of the continuous line forming the boundary of a shape. The word "circle" comes from the Greek "kirkos," which means ring. Aside from its importance in geometry, the circle is also used as a symbol of infinity, depicting a line that is never-ending.