We started compiling a directory (or catalogue as we call it here). To begin with, we’ve revisited a rather comprehensive list on Wikipedia. And we found something that confused us. Among “normal” social network sites, blogs, forums and collaboration sites were listed as well. Here’s when we started discussing, what exactly is the social network? Or what makes a network (or a website) the social network?

Let’s look around for help and some definitions.

Google suggests (I picked one of the suggested items) that social network is:

The personal or professional set of relationships between individuals.

Wikipedia’s view is:

A social network is a social structure made of nodes (which are generally individuals or organizations) that are tied by one or more specific types of interdependency, such as values, visions, idea, financial exchange, friends, kinship, dislike, conflict, trade, web links, sexual relations, disease transmission (epidemiology), or airline routes.

If you do more research, you’ll find different definitions (in terms of wording) for a social network, but generally it boils down to “group or related individuals”. Now, all above mentioned types of web sites fall under that definition. Whether it’s a collaboration site (such as wikipedia), or forum, or even Open Source Development site (such as SourceForge), or even a news site with their registered users, they all are social networks for they unite individuals in one or the other way. If you do more generalisation, the Internet is one big social network, because it unites all Internet users. That’s useful…

So, when it comes to sorting and identifying social networks, I believe we can distinguish two types: hard-linked and soft-linked networks.

Hard-linked networks are social networks where users pick their peers themselves. Theme of the network isn’t that much important. This type of network focuses on “friendship” and links between users. Examples of these networks are FaceBook, LinkedIn and MySpace. Linking is explicit, as links are picked by users themselves.

Soft-linked networks are social networks where users are “grouped” by some set of attributes, such as music they like, web sites they visit, software they develop or even company they work for. Linking in these networks does not play important role and in most cases is non-existent, because people already belong to a group. Exmpales of these networks could be any forum, news sites (Slashdot) or social bookmark sites (Delicious). Linking is implicit, as all group members are related by their attributes.

Surely, there are many gaps and holes in this definition, but for now, we’ll use this as a working theory for our catalogue.