It's one of the basic tenets of online security: Never use the same password/username combo for every website that requires one. The logic is sound, of course. A single security breach could expose your most private information — such as banking and credit card numbers — to the bad guys.

Problem is, who can remember multiple passwords and usernames? Many times I've signed up for a service, returned to the site a few weeks later, and quickly realized that I couldn't remember my login details.

Google and other major online players, including AOL, Facebook, Microsoft Plaxo, MySpace, and Yahoo, are pitching a simpler alternative: A single password/username combo, such as your Google or Yahoo ID, for multiple sites. The concept, based on the industry standard OpenID 2.0 protocol isn't exactly new. In fact, Google announced over a year ago that it would support the single single-in plan.

More: http://pcworld.com/article/181347/