---
tag: 0ZCK8DQYN1
kind: concept
name: Closed set
msc: [54A05]
sources:
  - url: https://en.wikipedia.org/wiki/Closed_set
    locator: lead section
same_as:
  wikidata: Q320357
  wikipedia: Closed set
---

## Summary

A closed set in a topological space is a set whose complement is open.
In a metric space, the closed sets are the sets that contain the limits of all their convergent sequences.