Recently someone at work asked me if I thought social networking on the Web was a fad. My response was that it depends on what you mean by social networking since lots of Web applications are lumped into that category but either way I think all of these different categories are here to stay.

I thought it would be useful to throw out a couple of definitions so that we all had a shared vocabulary when talking about the different types of Web applications that incorporate some form of social networking. A number of these terms were popularized by Mark Zuckerberg which is a testament to the way Facebook has cornered the thought leadership in this space.

1. Social Graph: If one were to render the various ways different people in a particular community were connected into a data structure, it would be a graph.  In a social graph, each person is a vertex and each relationship connecting two people is an edge. There can be multiple edges connecting people (e.g. Mike and I work at Microsoft, Mike and I are IM buddies, Mike and I live in Washington state, etc). Edges in the social graph have a label which describes the relationship. Fun examples of social graphs are slander & libel -- the official computer scene sexchart and the Mark Foley Blame chart.

2. Social Graph Application: An application that requires or is improved by the creation of a social graph describing the context specific relationships between it’s users is a social graph application. Examples of applications that require a social graph to actually be usable are instant messaging applications like Skype and Windows Live Messenger.  Examples of applications that are significantly improved by the existence of context specific social graphs within them are Digg, Flickr, Del.icio.us and Twitter which all don’t require a user to add themselves to the site’s social graph to utilize it’s services but get more valuable once users do. One problem with the latter category of sites is that they may require a critical mass of users to populate their social graph before they become compelling.

   Where Facebook has hit the jack pot is that they have built a platform where applications that are compelling once they have a critical mass of users can feed off of Facebook’s social graph instead of trying to build a user base from scratch. Contrast the struggling iLike website with the hugely successful iLike Facebook application.

3. Social Networking Site: These are a subset of social graph applications. danah boyd has a great definition of social networking sites on her blog which I’ll crib in it’s entirety; A "social network site" is a category of websites with profiles, semi-persistent public commentary on the profile, and a traversable publicly articulated social network displayed in relation to the profile. Popular examples of such websites are MySpace and Bebo. You can consider these sites to be the next step in the evolution of a personal homepage which now incorporate richer media, more avenues for self expression and more interactivity than our GeoCities and Tripod pages of old.

4. Social Operating System: These are a subset of social networking sites. In fact, the only application in this category today is Facebook.  Before you use your computer, you have to boot your operating system and every interaction with your PC goes through the OS. However instead of interacting directly with the OS, most of the time you interact with applications written on top of the OS. Similarly a Social OS is the primary application you use for interacting with your social circles on the Web. All your social interactions whether they be hanging out, chatting, playing games, watching movies, listening to music, engaging in private gossip or public conversations occurs within this context. This flexibilty is enabled by the fact that the Social OS is a platform that enables one to build various social graph applications on top of it.

By the way, on revisiting my schedule I do believe I should be able to attend the Data Sharing Summit on Friday next week. I'll only be in the area for that day but it should be fun to chat with folks from various companies working in this space and get to share ideas about how we can all work together to make the Web a better place for our users.