An Identity Provider, or IdP, is the enterprise system that proves who a user is and decides what that user is allowed to access. In practice, it sits behind single sign-on (SSO), multi-factor authentication, and policy rules that grant or deny applications, groups, and roles. Common examples include corporate login platforms that issue identity assertions or tokens to connected services.
IdPs matter because they are the control point for modern cloud access. When approvals, provisioning, and revocation flow through the IdP, security teams can enforce least privilege, automate onboarding and offboarding with SCIM, and reduce “shadow” access decisions made by individual users. But the IdP is also a high-value target: if an attacker compromises an admin account, abuses weak policies, or exploits a stale session, they may inherit broad access across many services. Strong MFA, careful admin separation, and regular entitlement reviews help keep the identity layer from becoming a single point of failure.