A rotation is a transformation that is done by turning a figure about a fixed point called the center of rotation. Rotations are often done in degree measures; for example, a 90o rotation. In general, geometric objects are rotated counterclockwise. An example of a rotation is shown below:

 Rotation Example

The segments drawn in red create an angle.  The measure of that angle in degrees is the amount the pre-image is rotated to create the image.