Latent Semantic Indexing (LSI) is the underlying root of the entire major search engines’ algorithms. There is a complicated Wikipedia version here http://en.wikipedia.org/wiki/Latent_semantic_indexing .. that goes into detail of the Matrix relationship of words, but to really understand it you will need some knowledge and understanding of Calculus and Advanced Algebra, and have not slept through the Derivatives and Matrices parts of class. I will attempt to show you a simplified version of it. Guess the theme/keyword of this next sentence:

“I love linguini, spaghetti, and angel hair. I also like rotini, bow ties, and macaroni.”

Here is the same concept of the sentence with stuffed keywords:

“I love pasta. All kinds of pasta. Without pasta, I couldn’t survive. There isn’t a type of pasta that I don’t like.”