IdP

A service that authenticates users and asserts identity to relying parties.

An identity provider authenticates users and issues trusted assertions or tokens about their identity to relying parties, enabling single sign on and federation so credentials are managed in one authoritative place. It is central to protocols such as SAML, OAuth, and OpenID Connect. It matters because consolidating authentication improves control but concentrates risk. A key pitfall is that the IdP becomes a high value target and a single point of failure: its compromise can grant access to every connected service, so it warrants strong protection and monitoring.