The XHTML Friends Network is a simple way to represent human relationships using hyperlinks. It’s almost trivial to add and appears to be a good idea from a semantic markup perspective, though there are very few XFN tools that actually utilitize it at this time. XFN enables web authors to indicate their relationships to the people in their weblog entries and blogrolls by simply adding a rel attribute to their anchor tags:
<a href="http://www.barik.net"
rel="friend met">Titus Barik</a>
Additionally, modify the profile attribute in the header to let browsers and search engines know that your pages officially support XFN:
<head profile="http://gmpg.org/xfn/11">
That’s all there is to it. But the best part is that the XFN standard uses the already existing W3C Recommendation to do its work:
**rel = link-types [CI]** This attribute describes the relationship from the current document to the anchor specified by the href attribute. The value of this attribute is a space-separated list of link types.
And also:
**profile = uri [CT]** This attribute specifies the location of one or more meta data profiles, separated by white space. For future extensions, user agents should consider the value to be a list even though this specification only considers the first URI to be significant. Profiles are discussed below in the section on meta data.
Welcome to the XHTML Friends Network. Looking forward to seeing XFN implementations in more weblog systems in the near future.
I believe Google is going to start using that as well, to prevent comment spam on websites. They use a ‘rel=nofollow’ or something like that. Didn’t feel like looking it up. Then they identify those tags as pages not to crawl, so as to prevent spammers from using to improve their pagerank.