17 Ways Search Engines Judge the Value of a Link, Rand Fish, SEOmoz Blog (Sept 10)
Illuminating article on the most important factors to a search engine in ranking results. It opens with the importance of links between domains.
"As you've likely noticed, search engines have become more and more dependent on metrics about an entire domain, rather than just an individual page. It's why you'll see new pages or those with very few links ranking highly, simply because they're on an important, trusted, well-linked-to domain. In the ranking factors survey, we called this "domain authority" and it accounted for the single largest chunk of the Google algorithm (in the aggregate of the voters' opinions). Domain authority is likely calculated off the domain link graph, which is unique from the web's page-based link graph (upon which Google's original PageRank algorithm is based). In the list below, some metrics influence only one of these, while others can affect both."
Posted by Gwen at September 11, 2009 05:52 PM