An Identity Provider (IdP) is a service that stores and manages user identities for enterprise customers, providing authentication services for their applications. Commonly used IdPs include Okta, OneLogin, PingFederate, Microsoft Entra ID, Google Workspace/Cloud Identity, ForgeRock, and Keycloak. IdPs offer various features such as authenticating users, managing user profiles, enabling Single Sign-On (SSO), handling authorization and access control, and managing authentication factors. Enterprises use IdPs for centralized identity management, SSO benefits, and improved security. WorkOS is a solution that helps developers implement SSO quickly and easily by providing SDKs and support for various protocols.