The answer? … Backlinks!
Two Stanford University PhD students, Sergey Brin and Larry Page, founded Google. At the time, search engines primarily relied on counting the number of times the keyword or search term appeared on a page. As you can imagine, this method rarely yielded the best results and was easily manipulated.
Being academics, Larry and Sergey knew of a better way to determine the relevance and credibility of a page. In academia, a major factor for determining the credibility and relevance of a piece of research is with the number of other pieces of research that cite it. If I reference your research within my own study then I’m saying that I’ve evaluated it and believe it to be of value.
Google determines relevance and credibility in a similar way to academia. If another page or website creates backlinks to your web page, then Google considers your page more credible and relevant. This is unsurprising when you consider Google’s original name was “BackRub”.
I know what you’re thinking, “It can’t be this simple, everyone always says how there are hundreds of constantly changing variables within the Google algorithm.” Well, they’re right, there are hundreds of criteria. However, the core design of Google has always been, and will always be, the same.
What can we learn from this? If you’re going to engage consultants for SEO, find out what their link building strategy will be for you. How many links do they expect to build? How will they build them? How long will it take to build them? How many do you need to rank at the top of search result pages? If these questions can’t be answered, then chances are you wont see an ROI on your search engine marketing investment.
On a side note, Stanford University still make the paper that Larry and Sergey wrote available on their site http://infolab.stanford.edu/~backrub/google.html. If you don’t like math it’s kind of a dry read, but it will shed light on the “mysteries” of Google rankings.