Single sign-on (SSO) provides the capability to authenticate once, and be subsequently and automatically authenticated when accessing various target systems. It eliminates the need to separately authenticate and sign on to individual applications and systems, essentially serving as a user surrogate between client workstations and target systems. Target applications and systems still maintain their own credential stores and present sign-on prompts to client devices. Behind the scenes, SSO responds to those prompts and maps the credentials to a single login/password pair. SSO is commonly deployed in enterprise, Web and federated models.