Introduction to OpenID Connect relying party
An "OpenID Connect relying party" is an OAuth 2.0 client application requiring end-user authentication and claims from an OpenID Connect provider (as defined in the Specification. Put in other words, a relying party relies on authentication information and claims issued by another entity. A common use case is to support login in a web application via an identity provider such as e.g., Google and PayPal.
In nevisAuth this functionality is implemented with the AuthStates OIDCProviderMetadataFetcherState, the RelyingPartyState and the UserinfoClientState.