OAuth 2.0 (Open Authorization 2.0)

An industry-standard protocol for authorization that allows a third-party application to obtain limited access to a user's protected resources on an HTTP service, without exposing the user's long-term credentials.

Closely related concepts include Access Token, Agent Hijacking, Machine-to-Machine (M2M) Authentication, SCIM (System for Cross-domain Identity Management). Each is defined in the Prefactor glossary.