Some of you who have been around for a while may have heard of LSI or latent semantic indexing. Search engines have a method for sorting websites into the correct category and ranking for the right search terms. LSI is one way they achieve this aim, and if you know how to use it, then it can improve your websites position in the serps.
So in a nutshell, latent semantic indexing is how the search engines associate words that are all similar or related to a certain topic. As an example, your website may be about plumbing. Google knows that the page should also contain related words, such as boilers, leaks, bathrooms, 24 hour callout, repair leaks etc.
This lets the search engines know what your subject is and how to organise the search terms. It knows that all the related words are refering to plumbing matters and not shopping or anything else. Once you have a list of related words and phrases, put them on pages of your website.
To find these related words pop over to the Google keyword tool and find all the related words the search engine finds relevant to the term. Then just use the words and phrases from your list to write or rewrite your content.
So instead of using traditional keyword percentages and density, use related phrases. Increasingly search engines are including LSI into search algorithms to evaluate your website pages better. And many experts now say that sites optimised for keywords can even rank lower as they are falsely over optimised.