Just when you thought you might be starting to understand how search engines compile their organic rankings, you stumble upon a new factor in the algorithm. While latent semantic indexing (LSI) isn’t exactly a new practice, it has been getting more attention as of late so we thought we’d take a moment to shed some light on it.

Latent semantic indexing…sounds pretty complicated doesn’t it? In actuality, there’s really not much to it. LSI is a search engine’s ability to identify synonyms and related terms for a keyword, and to identify pages as being related if they contain those similar terms. So if someone were to enter the search term “marketing,” the results that appear would include web pages that incorporate the words “communications” and “media” as well as those that contain “marketing.” In fact, the pages that contain the former don’t even necessarily have to mention the word marketing at all. The search engines will automatically make the connection between the words.

An important step in the indexing process, LSI not only records which keywords a document contains, but it also examines the document collection as a whole, to see which other documents contain some of those same words. According to LSI methods, documents that have many words in common are considered semantically close, and ones with few words in common are semantically distant. When you think about it, human beings might also classify a document collection using a method very similar to LSI. Unlike humans, the LSI algorithm doesn't understand anything about what the words mean…it simply notices patterns, which can make it seem astonishingly intelligent.

Any good copywriter would naturally incorporate words into a website’s content that relate to the subject at hand. The trick is not to over do it, adding so many keywords and synonyms that the copy begins to sound robotic and nonsensical. Because that sort of practice is transparent to website visitors and search engine spiders alike, it is certain to drive traffic away from your site and likely to get it penalized by the engines.

Latent semantic indexing (or similar technologies) can also be used to look at the link profile of your website. If all your links are heavy in a few particular phrases and light on other similar phrases then your site may not rank as well.

You can determine which words are related to your keywords by searching Google for search results with related terms. Do so by entering a “~” into the search bar directly in front of your search term. For example, to find words related to race car, you would key in “race car.” You’ll find results that include not only race car, but also racing, track, and NASCAR.

Another option is to look at variations of keywords suggested by keyword suggestion tools. You can also try writing a page and use the Google AdSense sandbox to see what type of ads they would try to deliver to that page. And still another way of determining related keywords is by reading the page copy and analyzing the backlinks of high ranking pages.

The lesson to be learned here is that while you’re concentrating on carefully incorporating your keywords into your website copy, don’t ignore the synonyms that correlate with those keywords. Your website will benefit from the conscientious eye of a skilled SEO copywriter…but keep our LSI tips in mind when writing your own content.

This article was written by Lillian Taylor, Senior Copywriter at Active Web Group