How LSI Keywords Work
This tool searches the top 10 in Google for a phrase you like to rank highly for. Then it collects all the text from these 10 result pages and calculate the most used words and phrases on these pages. It then orders them by number of times used. With this data you know exactly why these pages rank highly in Google. It’s all about theming and using LSI Keywords. For more proof and info about this subject read further.
I think that LSI stands for Latent Semantic Index.