The center of curvature of a curve is a point that is at a distance from the curve equal to the radius of curvature lying on the normal vector. It is the center of the sphere of which the spherical mirror is a part. The center of curvature is defined as the central part or the center point of a sphere of which the spherical or curved mirror is a part. The center of the spherical surface of which the mirror forms a part is called the center of curvature C of the mirror. The center of curvature is generally used in physics regarding the study of lenses and mirrors. The locus of centers of curvature for each point on the curve comprise the evolute of the curve. The evolute of a plane curve is defined as the locus of the centers of the osculating circles to the curve.