# 401 Unauthorized

No valid credentials were sent: sign in first.

## What is **401 Unauthorized**?

**401 Unauthorized** means "who are you?": no valid credentials were sent, or the token has expired. Despite the name, it is about authentication.

Level: Apprentice · [More Web Development terms at this level](https://www.ask-codey.com/glossary/subjects/web-development/apprentice)

Updated: September 27, 2026

Source: https://www.ask-codey.com/glossary/401-unauthorized