Single Sign-On, often shortened to SSO, is a login method that lets a user sign in once and then access multiple connected websites, apps, or internal tools without entering a separate password for each one.
How SSO works
With SSO, one trusted identity provider checks the user. After that, connected services receive proof that the user is already signed in. The apps do not all need to handle the password directly.
Why SSO is useful
SSO can reduce password fatigue, make account management easier, and help organizations apply stronger security rules in one place. It is often paired with two-factor authentication or passkeys.
What to watch for
Because many apps depend on one login system, the identity provider must be protected carefully. If that account is compromised, many connected services may be exposed.