Most people who have used the Internet, or even know what it is know what Google is. But most people don’t know what exactly it is that Google does.
Or rather what makes Google do what it does. Google searches are able to be so accurate because of Latent Semantic Indexing.
Latent Semantic Indexing allows a search engine to determine what a page is about by searching for one or more keywords selected by the user.
It adds an important step to the document index process. LSI records keywords that a document contains as well as examines the document collection as a whole.
By placing importance on related words, or words in similar positions, LSA has a net effect of making the value of pages lower so they only match specific terms.
Search engines such as Google try to figure out phrase relationships when they are processing keyword queries, which in turn improve the rankings of pages with related phrases.
This happens even when those pages are not focused on the target theme. Some pages are too focused on one phrase and they tend to rank worse than you would expect them to.
In fact, some are even filtered out for being too over...