What Is SSO? Single Sign-On Explained
A plain explanation of SSO (Single Sign-On): what it is and how it works. Why signing in once to reach many apps matters, and the mechanics behind it.
SSO (Single Sign-On) is an authentication method that lets you access multiple applications with a single login. The user signs in just once to a central authentication system, and the connected apps trust that authentication result, allowing access without a separate login.
Why SSO is needed
At a company where one employee uses five or six work apps every day, management gets complex fast when each app has its own ID and password. Users have to memorize several passwords, and administrators must open each app one by one to create and delete accounts at every hire and departure.
SSO reduces this complexity. Because accounts are managed in one place, you control password policy and access rights centrally, and you can check login records from one place too. This is also why enterprise customers demand SSO in security reviews.
How SSO works
At the center of SSO is an IdP (Identity Provider) that authenticates identity. The flow is roughly this: when a user reaches an app, the app delegates authentication to the IdP. When the user logs in to the IdP, the IdP passes "this user is authenticated" to the app, and the app trusts it and allows access.
The standard conventions for exchanging this information are OIDC and SAML. Whichever you use, the core is the same: the app does not receive the password directly and only verifies the authentication result of a trusted IdP.
A common misconception
SSO is not "unifying passwords into one." It is closer to a method that keeps apps from each storing passwords at all. Also, adopting SSO does not automatically connect every app. An app must support OIDC or SAML, and apps that do not need a separate approach.
The steps and readiness checklist for actually adopting SSO are covered in more detail in the SSO Adoption Guide for Small to Large Businesses. AxiPass is an IdP that supports both OIDC and SAML 2.0, so you can start for free and see the flow for yourself.