This document discusses OAuth 2.0 and OpenID Connect for accessing APIs. It provides an overview of how OAuth 2.0 allows clients to obtain access tokens to access protected resources from an authorization server, including the steps to obtain an authorization code and exchange it for an access token. It then introduces OpenID Connect as an identity layer on top of OAuth 2.0 that provides authentication as well as authorization and allows clients to verify the identity of the resource owner. The document promotes OpenID Connect as an improvement over traditional OpenID that supports API access and a better user experience.