Gerard Salton, who died on August 28 of 1995, was the father of modern search technology. His teams at Harvard and Cornell developed the SMART informational retrieval system. Salton’s Magic Automatic Retriever of Text included important concepts like the vector space model, Inverse Document Frequency (IDF), Term Frequency (TF), term discrimination values, and relevancy feedback mechanisms.
He authored a 56-page book called A Theory of Indexing which explained many of his tests upon which search is still largely based.