I would like to simplify Latent Semantic Indexing (LSI). LSI is an anti-spam algorithm. Instead of linking in all of the scholarly papers from those whose job with Google and other companies is to fight spam; I'm going to give you the down and dirty truth of what LSI is and why it is important to not just Google but all Internet entrepreneurs. First, I'd like to state that there has not been any published "laymen's" standards for LSI. My self and others have researched numerous interviews from Matt Cutts. Matt Cutts joined Google in January of 2000 and is now head of Google's Webspam team. You can visit Matt's blog at Mattcutts.com/blog/ for up-to-date information on how Google is fighting spam.