Single Sign On

Is "single sign on" becoming an English vocabulary term? What does it mean?  I think of a single sign on "SSO" to be a system where a single username and password can be used across a range of different facilities. For instance, Google and Wordpress and Twitter are use the OpenID credentials so that with the same identity, you can login to any site that accepts those credentials.

The seamless feature of single sign-on in this integration is an enormous step in making technology and programs like VocabularySpellingCity more accessible and practical in students' everyday learning.