---
tag: 0N6R902FG1
kind: concept
name: Monoid
msc: [20M10]
sources:
  - url: https://en.wikipedia.org/wiki/Monoid
    locator: Definition
same_as:
  wikidata: Q208237
  wikipedia: Monoid
---

## Summary

A monoid is a semigroup that has an identity element.
Examples are the natural numbers with addition and the maps from a set to itself with composition.