What Is an IdP? The Role of an Identity Provider
The definition and role of an IdP (Identity Provider), and how the system that authenticates identity plays the central role in SSO.
An IdP (Identity Provider) is a system that authenticates a user's identity and passes the result to multiple applications. It handles login in one place, and connected apps trust the IdP's authentication result. The IdP is exactly the core component that implements SSO.
What an IdP does
An IdP handles three main things: authentication, which confirms who the user is; authorization, which decides which user is allowed which access; and integration, which passes the authentication result to apps. On top of this, policies such as multi-factor authentication (MFA) enforcement and login auditing can be applied centrally at the IdP.
The relationship between IdP and SP
An app that trusts the IdP's authentication result and allows access is called an SP (Service Provider). When a user reaches an SP, the SP hands authentication to the IdP, and when the IdP finishes authenticating, it passes the result to the SP. The SP does not receive the password directly and only receives confirmation from the trusted IdP.
This trust relationship is formed by standard protocols such as OIDC or SAML. When you connect several SPs to one IdP, the user can use all connected apps with a single login.
What changes when you adopt an IdP
When accounts gather in one IdP, management becomes simpler. You grant a new hire access at once, and when you disable the IdP account at departure, access to connected apps is blocked together. Password policy and MFA are applied centrally, without needing per-app configuration.
The audit-side benefit is also large. Because logins go through the IdP, who accessed which app and when is recorded in one place, and this record is used directly as account and access management evidence in security audits. You do not have to gather logs scattered across individual apps one by one.
The order for actually selecting and adopting an IdP is covered in the SSO Adoption Guide for Small to Large Businesses. AxiPass is an IdP that supports OIDC and SAML, so you can start for free and examine the structure for yourself.