Single Sign-On (SSO) capabilities have been in existence for several years, yet the technology is still gaining steam. SSO technology was developed in response to a new security issue (and opportunity) that arose as organizations installed more enterprise-wide applications -- integrating new and legacy systems -- and enabled greater intranet/extranet access to employees, customers and vendors.

Single Sign-On has emerged as a significant technology that resolves a major issue for organizations with multiple platforms, servers and applications requiring unique usernames and passwords for access.

This paper, will discuss SSO's upside as well as the arguments against it. It will also review all the many different types of SSO that exist. By conducting this review, the goal is to facilitate understanding of all the different login methods that are considered SSO, but also get to the heart of what truly constitutes SSO in the current technological landscape.