Editing Social software (section)

=== Social network search engines ===
Social network search engines are a class of search engines that use social networks to organize, prioritize or filter search results. There are two subclasses of social network search engines: those that use '''explicit''' social networks and those that use '''implicit''' social networks.

*'''Explicit''' social network search engines allow people to find each other according to explicitly stated social relationships. [[XHTML Friends Network]] allows people to share their relationships on their own sites, thus forming a decentralized/distributed online social network, in contrast to centralized social network services listed in the previous section.
*'''Implicit''' social network search engines allow people to filter search results based upon classes of social networks they trust, such as a shared political viewpoint. This was called an [[epistemic filter]] in the 1993 "State of the Future Report" from the [[American Committee for the United Nations University]] which predicted that this would become the dominant means of search for most users.

Lacking trustworthy explicit information about such viewpoints, this type of social network search engine mines the web to infer the topology of online social networks. For example, the [[NewsTrove]] search engine infers social networks from content - sites, blogs, pods and feeds - by examining, among other things, subject matter, link relationships and grammatical features to infer social networks.