OAuth 2.0 established the standard for delegated authorization, allowing apps to securely access data on behalf of users without revealing their credentials. However, it was not designed to handle user identity, leaving a gap that OpenID Connect (OIDC) fills by layering on top of OAuth 2.0 and adding standardized authentication features. OIDC enhances existing OAuth flows with an authentication layer, allowing apps to verify who is logging in without extra calls or custom logic. It also introduces Discovery documents, dynamic registration, and a UserInfo endpoint, among other features, which unify the practices under a single specification. By reusing OAuth 2.0's authorization server infrastructure and providing a standardized way to confirm user identity, OIDC simplifies permission management, reduces redundant authentication logic, and streamlines user experience, making it a complementary use case for delegated authorization in modern applications.