The primary measurement used for Google's PageRank algorithm is the number and "value" of backlinks that a page has. The "value" of a backlink is determined by

The primary measurement used for Google's PageRank algorithm is the number and "value" of backlinks that a page has. The "value" of a backlink is determined by the cumulative number of descendent sub-backlinks that it has. This is common knowledge among SEO professionals. Basically, when judging quality, Google is making assumptions like: "This page has a lot of backlinks, and those backlinks themselves have a lot of backlinks... Therefore this page is of high quality." This approach puts all the power in the hands of content providers (bloggers) who are funded by big companies (or well-funded startups) and who serve the interests of those companies. Google wrongly assumes that content-providers serve the interest of consumers and that they can be trusted - Which is not the case.