Definition:Ring Automorphism

Definition
Let $\left({R, +, \circ}\right)$ be a ring.

Let $\phi: R \to R$ be a (ring) isomorphism.

Then $\phi$ is a ring automorphism. That is, a ring automorphism is a (ring) isomorphism from a ring to itself.

Also see

 * Definition:Automorphism (Abstract Algebra)