LSI – Short for ‘Latent semantic indexing’ is a system search engines use to analyze the other words people use surrounding a given topic. LSI keywords are words and phrases with a high degree of correlation to your target topic. Google’s algorithm uses them to help determine the content quality and relevance to the search term.
LSI keywords judge the quality of the content.
Search engines use LSI terms to judge the quality of the content on a page by looking for relevant words and key phrases that should appear alongside a given search term. Essentially LSI are suggestions for other terms users could search for in adding them to your content, the aim is that this increases the focus of what your page is about so that search engines can interpret relevance.
Where can I find LSI Keywords?
Look at the bottom of any search result page on Google. These related term searches supplied by Google are LSI keywords/terms. Working these terms into your content improves your relevancy and quality scores.