If a shape or image can be rotated less than 360 degrees and still retain the same appearance, this shape has rotational symmetry. For example, a five-pointed star can be turned to allow a different point to face upward and still appear as a five-pointed star; that's because this shape has rotational symmetry.
When discussing rotational symmetry, there is always a certain point around which the shape in question will be rotated. This point is known as the center of rotation. The smallest degree to which an image must be turned to retain its original shape is known as the angle of rotation.