The aim of this study was to review the studies carried out on recommender systems. Various databases were searched for keywords “recommender systems”, “collaborative filtering”, and “content filtering”. These studies were shortlisted as per the year of publication. Studies talk about the use of internet and World Wide Web being the reason behind the use of recommender systems today. Due to the advent of plethora of e-commerce and leisure websites, social media and a variety of search engines being used around the globe by millions of users today, there is an overwhelming amount of information being generated every second. In order to save the users from this information overload, recommender systems use users’ choices and make recommendations to them. Many of the studies reviewed have discussed collaborative and content filtering in recommender systems. Studies have talked about concepts such as novelty, diversity, unexpectedness, memorization and generalization in connection with recommender systems. Some studies have also talked about the social media and recommender systems. Active learning is another concept covered by a few of the studies which have been reviewed in this paper.

Keywords:Recommender System, Review, Trends, RS