A SAML identity provider (IDP) is a system or service that authenticates users and provides identity information to other applications using the Security Assertion Markup Language (SAML) protocol. In Single Sign-On (SSO) scenarios, the IDP verifies a user’s credentials and then issues SAML assertions containing authentication and attribute data. These assertions are consumed by service providers (SPs) to grant access to various resources without requiring the user to log in multiple times. SAML IDPs are commonly used in enterprise environments to centralize authentication, improve security, and enhance user experience by enabling seamless access across multiple applications. Examples include Microsoft Active Directory Federation Services (ADFS) and Okta.