2.4. Penetrating the Veil of Search Engine Secrecy

The search engines tell you a lot, but not the whole story. Search engines claim that the secrecy surrounding their algorithms is necessary because of malicious spammers, who would alter their sites deceptively for the sole purpose of higher rankings. It's in the search engines' best interests to keep their methods a secret; after all, if they published a list of dos and don'ts and just what their limits and boundaries are, then the spammers would know the limits of the search engines' spam catching techniques. Also, secrecy leaves the search engines free to modify things any time they need to. Google changes their algorithm frequently. For instance, in just six months in 2007, Google's algorithm changed 450 times. No one knows what changed, how big the changes were, or when exactly they occurred. Instead of giving out the algorithm, search engines merely provide guidelines as to their preferences. This is why we say that SEO is an art, not just a science: Too many unknown factors are out of your control, so a lot of finesse and intuition is involved.

Other factors can complicate rankings as well. Here's a brief list of factors that have nothing to do with changes on the Web sites themselves that can cause search engine rankings to fluctuate: