---
tag: 0TD904MG06
kind: concept
name: Orientable surface
aliases: [two-sided-surface]
msc: [53A05]
uses: [073JKP99K2]
sources:
  - url: https://en.wikipedia.org/wiki/Orientability
    locator: Orientable surfaces
---

## Summary

A surface in space is orientable if one can choose a [[unit normal vector|073JKP99K2]] at each point in a continuous way. The choice must be continuous over the whole surface.
Such a choice is an orientation. The Möbius strip is the standard surface that has no orientation.