I would disagree with "Guest The Google Team"'s assertion that every page listed has the phrase/words you're searching for on it somewhere. I often find when searching that some pages listed do not contain my search phrase ANYWHERE - this seems to be because the page has changed (and not necessarily recently, either) since it was listed by Google. And the now-irrelevant page always seems to be the one with the most promising lead, according to the quoted section on the search results page! Very frustrating. I don't know how often Google clean up their links, or even if they ever do, because almost every search I do contains a number of dead links to pages which no longer even exist.

Joan