Using the system of Latent Semantic Indexing (LSI) is one of the many website SEO strategies that SEO agencies and SEO professionals use to help search engines better analyze the overall theme of content on a particular webpage. These semantically relevant words and phrases have high degree of correlation to any given topic and are what Google algorithm used to gauge the quality of the content on the page and how relevant they are to the keyword being typed by the users. It is a must, therefore, to give priority to keyword optimization and use of the appropriate terms on your written content.