Recommendation engines are a technology that we all encounter several times in the course of a typical day. You meet the technology on e-shop where it drives the feature that gives customer suggestions on a similar product to buy. The technology is also used on Netflix to suggest which next movie to watch, or which songs on Spotify that are most similar to the ones we have on our playlist or to find similar books on Amazon.
Thus, it is primarily a commercial technology that relates to products and services.
It is primarily among the seven on the list because of its high degree of use. It serves a very specific purpose, namely, to find the products or services that match a given user’s behavior.
The book on Recommendation Engines that I can recommend the most is a part of The MIT Press Essential Knowledge series. It is simply called “Recommendation Engines”, and is written by Michael Schrage