By Mike Grehan at Search Engine Watch

It’s been 10 years since I wrote the second edition of a book about search engines called “Search Engine Marketing: The Essential Best Practice Guide”. It was a very big seller and, in fact, it carried on selling through to the beginning of 2010 when I took it offline.

I’ve decided to start this year by revisiting the chapter in the book about how search engines work. I’ve said many times over the years that, most books about SEO have a section called how search engines work. But rarely (if ever) do they describe the interdisciplinary approach to information retrieval (IR) covering mathematics, computer science, library science, information architecture, cognitive psychology, linguistics, and statistics – to name but a few.

Previously, I had written mainly about methods of manipulating rankings by keyword stuffing and other black hat type techniques of the time. But as I began to realize the importance of linkage data and even more so, link anchor text, I became more and more inquisitive as to what it was exactly that search engines used in their ranking technologies.