XFN is a technical term that is an acronym that stands for “XHTML Friends Network.” This is primarily used by websites that want to create a series of referral links between other websites in order to boost SEO ratings.
XFN links must follow a a certain format, to wit:
(a href=”http://www.photomatt.net/””” rel=”friend”)Photo Matt(/a) using the “<” and “>” signs respectively instead of open and closed parenthesis.
Bloggers primarily use XFN in order to demonstrate that they are friends or colleagues with the people who own or operate other blogs. The rel=”friend” tag inside the link is the attribute that demonstrates this friend relationship. You can also further classify the kind of friendship you have with the other website by modifying the attribute (for example: rel=”friend I met at a WordCamp”, but just a simple “friend” is the most common usage of XFN.
Search engines and other specialized services will parse these XFN links to understand and display the relationship you have with the owners or operators of these external sites.
XFN is what’s known as semantic content because it adds more meaning to the information available on your website and your relationship with other people’s sites.