Automorphism

Summary

An automorphism of a structure is an isomorphism from the structure to itself. It is a symmetry of the structure: a permutation of its elements that keeps all operations and relations. The automorphisms of a structure form a group under composition, the automorphism group. Complex conjugation, as an automorphism of the field $\C$, and the Frobenius automorphism of a finite field are classical examples.