what are recommender systemswelllike said amazon is great exampleand one ' very familiar with soif you go to their recommendations sectionas shown in the following imageyou can see that it will recommend things that you might be interested in purchasing based on your past behavior on the site the recommender system might include things that you've ratedor things that you boughtand other data as well can' go into the details because they'll hunt me downand you knowdo bad things to me butit' pretty cool you can also think of the people who bought this also bought feature on amazon as form of recommender system the difference is that the recommendations you're seeing on your amazon recommendations page are based on all of your past behaviorwhereas people who bought this also bought or people who viewed this also viewedthings like thatare just based on the thing you're looking at right nowand showing you things that are similar to it that you might also be interested in andit turns outwhat you're doing right now is probably the strongest signal of your interest anyhow