OAuth 2.0 is an authorization framework that enables third-party applications to obtain limited access to an HTTP service.

Authorization Flow

1. User is redirected to the authorization server.
2. User grants permission to the application.
3. Authorization server redirects back with an authorization code.
4. The application exchanges the code for an access token.
5. The token is used to access protected resources.

OAuth decouples user authentication from the service being accessed, improving security and scalability.