Bill Slawski has written up another interesting piece about how search engines substitute other search terms for yours depending on past user behavior. Of course, this is related to a patent he discovered that was filed by Yahoo.

Bill explains how this works:

Therefore, it’s important to take these other substitutions into consideration when optimizing your page, according to a Cre8asite Forums post. It is helpful to look at the various suggestions and optimize accordingly.

Forum discussion continues at Cre8asite Forums.