Latent semantic indexing (LSI) allows search engines to determine the topic of a page outside of directly matching search terms. LSI models the contexts in which words are used to find related pages, similar to how humans understand language through context. LSI was introduced to search engines by Applied Semantics and acquired by Google to power adsense through finding related ads. LSI gives search engines the ability to return more relevant results to users by understanding related terms, synonyms, singular/plural forms, and words with similar meanings or roots. Implementing LSI in a website involves developing thematically focused content using related keywords and synonyms throughout to better match user intent.