Last weekend (during the superbowl, actually), I sat down and read a bit about OpenID. There's still plenty I want to read about it, and experimenting to do with it. But as several other pages have pointed out, OpenID got a big boost today, and I felt like talking about it. OpenID is a good thing. Not just in general, but for you, personally.
What openid (I'm too lazy for all those caps) does for you, at the most basic level, is ease password management. Most popular webpages have some sort of login requirement. Which means that every time you want to use a new webpage, you have to sign up again, pick a username and password (making a new one you'll forget, or using the same one everywhere - so that if somebody knows your password in one place, they can pretend to be you anywhere online), enter whatever personal information... etc. And it's a pain. With openid, you pick one place (there are lots of options, and you can even run your own; there's no reason you only need one, of course) that you will use as your personal login hub. Then, for sites that support openid, logging in becomes much easier. Instead of remembering your username and password for that particular site, you tell the site where you have your openid (you specify a url). The site then redirects you there, and you log in at this one central (for you) location. After logging in, you approve the request to use your openid at the site you want, and you get redirected back to the site you wanted in the first place. Your openid provider then acknowledges, to the webpage that you wanted, that you logged in. So, yes, it does seem like an extra step. But it really isn't much, especially when you consider the convenience of one central place to log in.
For example, I registered for an openid at myopenid.com as 'imanidiot'. So if a webpage 'A' requests my openid so I can log in, I tell them 'imanidiot.myopenid.com' (not telling 'A' any password). I get re-directed to imanidiot.myopenid.com, log in (actually, myopenid lets you use digital certificates, so you can easily stay logged in, or log in just by pressing a button (instead of remembering a password)), tell myopenid.com that, yes, I would like to let 'A' know that I have logged in successfully. Then myopenid says ok, and I am back to 'A's page. In the background, 'A' asks myopenid if I really logged in, and myopenid tells them I did (because I told it to).
Depending on your openid provider, you might get additional functionality. For example, at myopenid I can create profiles (you can to, if you register). Then when I want to log in at 'A', I pick a profile to send them (with, say, a nickname, email, picture...) and 'A' can use this information for my profile at 'A'. Handy. I honestly don't know the advantages of differing providers. I didn't want to have to create accounts at them all to find out...
So, you want to try it out, huh? Luckily, you might already have an openid provider. If you have an aol (or aim) account, say 'myaimname', then check out 'openid.aol.com/myaimname'. Yahoo users also have openids through yahoo. If you have an account on blogger, you can use it as your openid provider (you just have to click the check-box in the appropriate privacy page, it's experimental). Otherwise, you'll have to sign up somewhere (the last sign up you'll ever need?). For options (and more sites that might already be giving you an openid), see this list. If you want to try logging in at some site that uses openid, the one I've been pretending to use is plaxo.com (for no particularly good reason, except they've been in the news recently). They also let you log in without openid, but what fun is that?
Anyway, that's a brief intro. I suggest reading more (I know I want to), and if you haven't read any, openid.net is the place to start. If you already know about it, and I used the wrong terminology above in any place, please forgive me.
Guess that's about it for today. I gave a talk today on p-adics, and am planning on typing something up this weekend. There's something for you to look forward to.