"FOAF" -- short for Friend-Of-A-Friend -- offers a vocabulary for putting machine readable code into a webpage, making it possible to link from one site, person, company, etc to related ones. It's been evolving since 2000, but seems on the edge of a major break-out. Now's a good time to learn about it and ride the wave of its growth.
FOAF is part of the semantic web movement, a philosophy and method of using technology to be able to reach, combine, and react to discrete information coming from multiple sources. Put simply, it lets you (or your system) get to very specific bits of information from many web pages or systems, even if they're not yours. Of course, as this technology develops, you'll only be able to reach the discrete bits of data that you're allowed to (more about that some other time).
If you think about it, the concept of machine-readable Friend-of-A-Friend data would seem to eliminate the need for LinkedIn, FaceBook, MySpace, and all the rest. In theory, you wouldn't need these services because you could pull together your networks by first, second, and nth degree of separation automatically. You could see networks of friends, business associates, or whatever directly from everyone's pages. But, in that surprising way the web works, that's not how it's going to happen exactly.
A few weeks ago, I had the distinct pleasure of meeting Dan Brickley, creator of FOAF. From him, I learned that software is going to start linking FOAF data with other machine-readable social network information. The way I understand it, smart folks at places like Google and Yahoo are providing code (APIs) that will let you bridge data from FOAF with data from places like Flickr and Twitter. So they'll be able to make the jump from one social network to the next. If FOAF knows Amy is my friend; Twitter knows I share what I'm doing with Bobby; and Flickr knows I share my pictures with Cindy, these APIs will pull that information together and know that I know Amy, Bobby, and Cindy. These relationships can be displayed in "social graphs", visualizations that look like linked Tinker Toys where every bubble is a person.Flickr and Twitter are out front on this one because they, too, put data in code that's directly accessible to the web.
The big ideas here are:
1) People won't have to keep entering the same information to get the same people into new social network websites. If Twitter knows that I know Cindy, but she's not in my Twitter group, it can ask me if I want to include her. This is HUGE. There are millions of people joining networks all the time and one that offers this no-typing option will have a big competitive advantage.
2) People won't have to have their data stored with a particular website. They could have their data stored anywhere and just use websites that offer network topics or services, bringing together the right data only for the moment they need it. So, you wouldn't have to permanently set up accounts of all your friends on a wine tasting network because you wanted them to share an event there one time.
3) Applications will grow up around this, offering ways to segment relationships into different levels of access. Just because the web can see that your mom and your girlfriend are both connected to you doesn't mean you want to share the same things with them.