Latent Semantic Indexing (LSI) can be a little confusing and seem overwhelming to those of us who want a hard and fast rule for reaching the perfect keyword density in our web pages. I’m going to break down the concepts behind LSI, and give you a couple tips to make it simple to find out what Google really wants.

LSI has been around as an SEO hot topic for several years, but gained in popularity when Google mentioned using LSI as one way to determine the relevancy of a page, in their patent application.

So, What is LSI?

There are all kinds of technical explanations and mathematical formulas to explain latent semanic indexing, but for our purposes, here’s a simplified definition:

LSI is a technology that Google and other search engines use to determine how your web pages should be ranked. It decides which words are semantically related to each other and then expects to see those words on your page in order to rank well for your keyword. A more thorough definition of LSI can be found at SEObook.

Long gone are the days of stuffing the same keywords throughout your pages to get them ranked. Google adopted LSI technology in their algorithm to prevent the old keyword spamming techniques. Now we need to use keyword variations and semantically related keywords throughout the page.

For example, if you have an article about the “President of the United States”, Google will now expect to see the words “White House” or “George W. Bush” also in the article.

LSI Keywords

So, how do you find out which keywords Google thinks are related? There are two quick and easy ways to find out what Google thinks are related keywords.

The first method in finding LSI keywords is in Google’s own search results. When you type your main keyword into Google, the search results page will display a list of related searches. In the example below, my keyword was “search marketing”, and you can see that Google thinks that good LSI keywords for that topic include “search engine marketing”, “search engine optimization”, “internet marketing”, “website marketing”, and even “yahoo pay per click”.

You can even drill down even further by clicking on any one of these related searches and finding a new list of related searches, as shown below when I click on “search engine marketing”.

The other way to find lsi keywords is through Google Adwords’ Keyword Tool. You simply enter your main keyword and check the box “Use Synonyms”, and Google will give you a list of relevant search terms, along with other helpful information like average search volume and advertiser competition.

Next time you’re writing a blog post or an article for your web site, do a quick search on Google first to get 5-8 LSI keywords you can easily weave into your writing. It will make a big difference in your rankings!