Definition:Symmetry Mapping

Definition
A symmetry mapping of a geometric figure is a bijection from the figure to itself which preserves the distance between points.

In other words, it is a self-congruence.

Intuitively and informally, a symmetry mapping is a movement of the figure so that it looks exactly the same after it has been moved.

Also known as
A symmetry mapping is often referred to just as a symmetry.