So I'm cruising around town the other day, doing what I often do while I should be paying attention to the road — thinking.
Google uses something they call Pagerank to rate website popularity based on how websites link to other websites.
PageRank relies on the uniquely democratic nature of the web by using its vast link structure as an indicator of an individual page's value. In essence, Google interprets a link from page A to page B as a vote, by page A, for page B. But, Google looks at more than the sheer volume of votes, or links a page receives; it also analyzes the page that casts the vote. Votes cast by pages that are themselves “important” weigh more heavily and help to make other pages “important.”
Important, high-quality sites receive a higher PageRank, which Google remembers each time it conducts a search. Of course, important pages mean nothing to you if they don't match your query. So, Google combines PageRank with sophisticated text-matching techniques to find pages that are both important and relevant to your search. Google goes far beyond the number of times a term appears on a page and examines all aspects of the page's content (and the content of the pages linking to it) to determine if it's a good match for your query.
But with Google's increasing success, I often find myself linking to a Google search for a subject I'm writing about rather than a particular website with information about the subject. (i.e., if I'm writing about salt-water aquariums, I can link it to a Google search of salt-water aquariums rather than a particular site about salt-water aquariums )
This isn't a big deal until Google's success reaches a critical mass and more websites start linking to Google searches of the subject rather than a direct link. Then the Pagerank system will not be able to use the direct links to judge the usefulness of the sites in question.
I'm sure the great folks over at Google have thought about this and have alternate methods in place, but it's something that makes me think.