Reflection

A reflection in the plane has the effect of transforming an object in the plane onto its mirror image. Thus under reflection in the plane a figure in the plane is effectively flipped over a fixed line in the plane. The points on this line (called the mirror line or line of reflection) are the only fixed (invariant) points of the transformation. A reflection in space has a plane of reflection, that is, a plane of points that are invariant under the transformation of reflection. A reflection is a shape-preserving (isometric) transformation.