/ˈaɪ-dē-ˈpē/
n. “The authority that says who you are.”
IdP, short for Identity Provider, is a service that creates, maintains, and manages identity information for users and provides authentication to relying applications or services. In modern digital ecosystems, an IdP is the linchpin of single sign-on (SSO) and federated identity systems, enabling secure and seamless access across multiple platforms.
The primary function of an IdP is to authenticate a user’s credentials—such as username/password, multi-factor authentication, or even biometrics—and then assert the user’s identity to other services. These assertions are typically delivered using protocols like SAML, OpenID Connect, or OAuth.
For instance, when you click “Sign in with Google” on a third-party website, Google acts as the IdP. It confirms your identity and tells the website that you are who you claim to be, without exposing your password. This abstraction allows multiple applications to rely on a single, trusted identity source while reducing password fatigue and improving security.
IdPs also manage user attributes, such as email addresses, roles, group memberships, and access permissions. These attributes are often essential for authorization decisions, enabling fine-grained access control in enterprise environments. Organizations may deploy internal IdPs to govern employee access or leverage cloud-based IdPs for external applications.
Security is a critical concern for any IdP. Compromise of the IdP can expose all connected applications, which is why modern providers implement rigorous authentication methods, encryption, and compliance with privacy regulations such as GDPR or CCPA.
Examples of IdPs include Microsoft Azure Active Directory, Okta, Auth0, and Google Identity. Each serves as a central point to authenticate users and provide trusted identity assertions to connected services, whether for enterprise applications, SaaS platforms, or web portals.
In summary, an IdP is the digital authority that manages identity, authenticates users, and asserts their credentials to relying services. It reduces friction, centralizes identity management, and provides a secure, auditable framework for modern authentication and access control.