There has been a lot of buzz recently in our industry about “Latent Semantic Indexing” or LSI. It’s being implemented in varying degrees by many search engines, including Google. So it is something you should be aware of as it will impact your site’s visibility and rankings.
Though LSI sounds complicated, it really just has to do with a search engine's ability to identify synonyms and related terms for a keyword. The engine indexes relevant pages based on all the related terms, not just the one you may have included in your search query.
For example, for a search on "cars," a search engine employing LSI might return high-ranking results with pages about autos, trucks, SUVs, or minivans that have significant use of words synonymous with cars. In other words, with LSI, the search engine is smart enough to know that pages containing related terms might be relevant to someone searching for information on “cars.”
LSI and SEO
LSI not only rewards searchers, LSI (along with other SPAM filtering programs used by search engines) rewards “white hat” search engine optimization link-building and content-building techniques and further penalizes “black hat” work-arounds. Simple repetition of keywords won’t get you better visibility with LSI-enhanced engines. It is the context and right combination of all the words in your content that really matters now.