The document discusses the role of an identity broker and its key functions. An identity broker acts as a centralized hub that can connect to multiple identity providers and service providers in a protocol-agnostic manner. It allows for identity federation across different protocols and systems. The broker supports important identity management capabilities like claim transformation, home realm discovery, multi-factor authentication, adaptive authentication, identity mapping, attribute aggregation, and just-in-time provisioning in a centralized manner. Fifteen fundamentals of the identity broker pattern are described. The document also discusses the concept of an identity mediation language and seven fundamentals of future identity and access management.