The cornerstone of the entire gigantic edifice that is Google is based on the same calculation that search engine optimization (SEO) practitioners make every day, according to a story in Wired Magazine: The inbound link.
Steven Levy writes that "the story of Google’s algorithm begins with PageRank, the system invented in 1997 by cofounder Larry Page while he was a grad student at Stanford. Page’s now legendary insight was to rate pages based on the number and importance of links that pointed to them – to use the collective intelligence of the web itself to determine which sites were most relevant."
Google’s algorithm is adjusted frequently, a process that Google engineer Amit Singhal described to Wired as "basically [changing] the engines on a plane that is flying at 1,000 kilometers an hour, 30,000 feet above Earth."
Experts say that PageRank’s basic functionality is not only the foundation of Google’s success in the search market, it is the foundation of the search engine optimization (SEO) industry’s success in providing their services to their clientele.
