They are security tokens that contain information about a user’s identity and authentication status and rely on OpenID Connect (OIDC), a free authentication standard. ID tokens are relevant in single sign-on (SSO) authentication procedures such as OAuth 2.0 and assure that a user’s identity is legitimate throughout the authentication operations.
Purposes :
Provides info about user to the RP (Relying Party)
Proves user’s authentication by the IDP (Identity Provider)
Enables SSO
Implements authorization policies based on user’s attributes or roles