Wish everyone would support single sign on?
Tired of implementing secure reliable account systems?
Originally developed to handle authentication when commenting across different blogs, OpenID is an extremely simple single-sign-on authentication system designed to assert your ownership of a URL. Designed in an open format, it is completely decentralized so it will survive unlike other comparable systems which rely on a centralized service to provide authentication. OpenID is also designed with an incredibly low barrier of entry, so that it can be used by large services such as LiveJournal.com as well as by users on $1.99 a month shared hosting.
OpenID is currently the largest open source and decentralized single-sign-on system in existence. While OpenID is not a trust or reputation system, or the answer to the Metasystem as defined by Kim Cameron in May of 2005, it does provide an easy to implement foundation to build valuable services on top of.
Discover the design decisions made while developing OpenID and how you can use it to allow your users to become OpenID enabled, or give you access to the over twelve million OpenID users out there.