---
tag: 0Q8Y862DTZ
kind: concept
name: Outer automorphism group
msc: [20F28]
sources:
  - url: https://en.wikipedia.org/wiki/Outer_automorphism_group
    locator: lead section
same_as:
  wikidata: Q77980689
  wikipedia: Outer automorphism group
---

## Summary

The outer automorphism group of a group is the quotient of its automorphism group by the inner automorphisms.
It measures how many automorphisms do not come from conjugation.