OpenID is one of the most exciting projects/standards released in the recent years on the web. I am quoting its definition from the wikipedia:

OpenID is an open, decentralized standard  for authenticating users which can be used for access control, allowing users to log on to different services  with the same digital identity where these services trust the authentication body.

OpenID replaces the common login process that uses a login-name and a password, by allowing a user  to log in once and gain access to the resources of multiple software systems.

Basically what it all says is: you have a single password with your OpenID provider and with it you are able to register and login to any OpenID enabled website.

And why should you demand OpenID support from your favorite websites? Basically it all comes down to not having to remember dozens of passwords for each account you have, or even worse, to not use the same password for each one of them.

By centralizing your authentication with an OpenID provider you are able to create a single (and very strong) password that will authenticate you to any website you use.

You can obtain an OpenID from some very popular websites such as:

• Google Profiles (see here how)
• Flickr (see here how)
• and many others

If your favorite webiste does not currently support OpenID, you can join the rest of the guys on this website and demand it. Hopefully we will be heard.