# What is Single sign-on?

> Using one account to sign in to many services, so credentials are held in one place.

Last reviewed: 2026-09-01

## Single sign-on

Category: Authentication

Also called: SSO, sign in with Google, social login

Canonical page: https://moolkey.com/glossary/single-sign-on

Single sign-on lets one identity provider vouch for you across many services through a button such as 'Sign in with Google' or 'Sign in with Apple'. It reduces the number of passwords you hold and concentrates the consequences: whoever controls that provider account can reach every connected service.

### The genuine benefits

Fewer passwords means fewer chances to reuse one. The identity provider is usually better defended than a small site would be, and it can enforce strong second factors centrally. For organisations, revocation is also immediate because disabling one account closes every connected service.

### The concentration cost

Losing the provider account can cut off every connected service, and providers do suspend accounts. Some services also make it hard to detach a social login later. Protect the SSO account itself with a security key and keep its recovery methods current.

### Sources

- [NIST: SP 800-63C-4: Federation and assertions](https://csrc.nist.gov/pubs/sp/800/63/c/4/final): Current guidance for federated identity and single sign-on.
- [OWASP: Multifactor Authentication Cheat Sheet](https://cheatsheetseries.owasp.org/cheatsheets/Multifactor_Authentication_Cheat_Sheet.html): A comparison of authentication factors, recovery paths, and common attack routes.
- [NIST: SP 800-63B-4: Authentication and authenticator management](https://csrc.nist.gov/pubs/sp/800/63/b/4/final): Current requirements for passwords, authenticators, recovery, and rate limits.