A one-time authorization method used to gain access to multiple applications or independent resources on one or more websites. If, say, a user signs into their account in an online store that supports SSO, there will be no need to re-enter their authorization credentials to use the tech support chat or customer forum.
Besides the obvious advantages, SSO has some drawbacks. For example, it makes password security even more important, since an attacker could gain access to all sections of the portal having just one password.