Single Sign On is a technology that allows a single login to be transparently used with multiple applications and environments.
Single Sign On (SSO) is a technology that allows the transparent use of a single username and password in multiple security domains. They're commonly used as part of a greater identity-management framework which unites otherwise separate systems into a single virtual login domain. SSO systems may be purely web-based, or client-based.
A variety of technologies can be used to build SSO systems.
