This section is informative.
This publication and its companion volumes, [SP800-63], [SP800-63A], and [SP800-63B], provide technical guidelines to organizations for the implementation of digital identity services.
This document, SP 800-63C, provides requirements to identity providers (IdPs) and relying parties (RPs) of federated identity systems. Federation allows a given IdP to provide authentication attributes and (optionally) subscriber attributes to a number of separately-administered RPs through the use of federation protocols and assertions. Similarly, RPs can use more than one IdP as sources of identities.