On November 16th 2003, Google commenced an update (the Florida update) which had a catastrophic effect for a very large number of Websites, and, in the process, turned search engine optimization on its head. It is usual to give alphabetical names to Google's updates in the same way that names are given to hurricanes, and this one became known as "Florida".
In a nutshell, a vast number of pages, many of which had ranked at or near the top of the results for a very long time, simply disappeared from the results altogether. Also, the quality (relevancy) of the results for a great many searches was reduced. In the place of Google's usual relevant results, we are now finding pages listed that are off-topic, or their on-topic connections are very tenuous to say the least.
The Theories About The Florida Update
The various search engine related communities on the web went into overdrive to try and figure what changes Google had made to cause such disastrous effects.
SEO filter: One of the main theories that was put forward and that, at the time of writing, is still believed by many or most people, is that Google had implemented an 'seo filter'. The idea is that, when a search query is made, Google gets a set of pages that match the query and then applies the seo filter to each of them. Any pages that are found to exceed the threshold of 'allowable' seo, are dropped from the results. That's a brief summary of the theory.
At first I liked this idea because it makes perfect sense for a search engine to do it. But I saw pages that were still ranked in the top 10, and that were very well optimized for the searchterms that they were ranked for. If an seo filter was being applied, they wouldn't have been listed at all. Also, many pages that are not SEOed in any way, were dropped from the rankings.
Searchterm list: People realized that this seo filter was being applied to some searchterms but not to others, so they decided that Google is maintaining a list of searchterms to apply the filter to. I never liked that idea because it doesn't make a great deal of sense to me. If an seo filter can be applied to some searches on-the-fly, it can be applied to all searches on-the-fly.
LocalRank: Another idea that has taken hold is that Google has implemented LocalRank. LocalRank is a method of modifying the rankings based on the interconnectivity between the pages that have been selected to be ranked; i.e. pages in the selected set, that are linked to from other pages in the selected set, are ranked more highly. (Google took out a patent on LocalRank earlier this year). But this idea cannot be right. A brief study of LocalRank shows that the technique does not drop pages from the results, as the Florida algorithm does. It merely rearranges them.
Commercial list: It was noticed that many search results were biased towards information pages, and commercial pages were either dropped or moved down the rankings. From this sprang the theory that Google is maintaining a list of "money-words," and modifying the rankings of searches that are done for those words, so that informative pages are displayed at or near the top, rather than commercial ones.
Google sells advertising, and the ads are placed on the search results pages. Every time a person clicks on one of the ads, Google gets paid by the advertiser. In some markets, the cost per click is very expensive, and the idea of dropping commercial pages from the results, or lowering their rankings, when a money-word is searched on, is to force commercial sites into advertising, thereby putting up the cost of each click and allowing Google to make a lot more money.
Comment on the above theories: All of the above theories are based on the idea that, when a search query is received, Google compiles a set of results and then modifies them in one way or another before presenting them as the search results. All of the above theories are based on the premise that Google modifies the result set. I am convinced that all the above theories are wrong, as we will see.
Stemming: Finally, there is a theory that has nothing to do with how the results set is compiled. Google has implemented stemming, which means that, in a search query, Google matches words of the same word-stem; e.g. drink is the stem of drink, drinks, drinking, drinker and drinkers. So far, this is not a theory - it's a fact, because Google says it on their Website. The theory is that, stemming accounts for all of the Florida effects. Like the other theories, I will show why this one cannot be right.
Evidence
There are a number of evidences (Florida effects) that are seen in the results, but I won't go into detail about them all. One piece of evidence that everyone jumped to conclusions about is the fact that you can modify the searches to produce different results. For instance, a search for "UK holidays" (without quotes) shows one set of results, but if you tell Google not to include pages that contain a nonsense word, e.g. "UK holidays -asdqwezxc" (without quotes), you will get a different set of results for some searches, but not for others. Also, the results with the -nonsense word looked the same as they were before the update began, therefore they appeared to be the results before a filter was applied.
This is what led people to come up with the idea of a list of search terms or a list of money-words; i.e. a filter is applied to some searches but not to others. It was believed that the set of results without the -nonsense word (the normal results) were derived from the set produced with the -nonsense word. But that was a mistake.
Stay tuned for Part 2 and find out what really happened, and what's coming next...
Editor's Note: This is the first in a series of articles about Google from our friends at PerlCoders. The information which we'll present here will help you to maximize your rankings on this popular traffic source. Enjoy! ~ Stephen