A circle is a simple geometric shape defined as the set of all points in a plane that are equidistant from a central point, known as the center. The distance from the center to any point on the circle is called the radius. The total distance around the circle is called the circumference, which can be calculated using the formula C = 2\pi r, where r is the radius and \pi (pi) is approximately 3.14. Circles are commonly found in everyday life, from the wheels of vehicles to the shape of coins. They are also important in various fields such as mathematics, engineering, and art. In mathematics, circles are studied in relation to other shapes and are used in concepts like geometry and trigonometry.