A recommendation system (that is, recommendation engine or RE) is a subclass of information filtering systems that helps predict the rating or preference based on the ratings given by users to an item. In recent years, recommendation systems have become increasingly popular. In short, a recommender system tries to predict potential items a user might be interested in based on history for other users.

Consequently, they're being used in many areas such as movies, music, news, books, research articles, search queries, social tags, products, collaborations, comedy, restaurants, fashion, financial services, life insurance, and online dating. There are a couple of ways to develop recommendation engines that typically produce a list of recommendations, for example, collaborative and content-based filtering or the personality-based approach.