How Does Google Determine Which Web Sites Are the Most "Trusted"? The new online edition of Google Librarian Newsletter is now available.
There are two short articles included. This is one of them. It is written by Matt Cutts, Software Engineer, Google. He is well know on the Web from his Matt Cutts: Gadgets, Google, and SEO blog which gives tips to Webmasters.
The article does explain the basics of how Google determines which sites are trusted. If you have done no research on this topic, you will find this of interest. If you are one of the many librarians who has already done research and discussed this topic with other librarians, there is probably nothing new here. (Do I work at the only Reference Desk in the world where reference librarians discuss the Google "secret sauce", read threads at SEO forums like WebMaster World, and use what we learn to modify our library instruction lesson plans and help patrons find information? I think not. Perhaps Google has not realized how educated many librarians are about how Google works already.)
From the site:
This question goes to the heart of what we do. You already know the short answer: Google uses more than 100 different factors, including the PageRank algorithm, to determine whether a site is trusted or reputable. If you think of the internet as a democracy, a web page that links to another page is "voting" for the value of the page. As we explain in our Technology Overview, PageRank interprets a link from Page A to Page B as a vote for Page B by Page A. PageRank then assesses a page's importance by the number of votes it receives. But that's not the end of the story. If Page A itself has more votes from other pages, the vote carries more weight. Or to put it another way, if more people trust your site, your trust is more valuable.
In addition to using the PageRank algorithm, we automatically analyze the content of pages we crawl. This goes beyond scanning page-based text, which webmasters can easily manipulate through meta-tags. We also look at factors like fonts and the placement of words on a page. And we examine the content of neighboring pages, which can provide more clues as to whether the page we're looking at is trusted and will be relevant to users.