A 원 (circle) is a simple geometric shape defined as the set of all points in a plane that are equidistant from a fixed point called the center. The distance from the center to any point on the circle is known as the radius. Circles are commonly found in nature and human-made objects, such as wheels and coins. In mathematics, the properties of a circle are studied in various contexts, including geometry and trigonometry. The circumference, or the distance around the circle, can be calculated using the formula C = 2\pi r, where r is the radius. The area of a circle is given by the formula A = \pi r^2.