For instance, suppose someone made a playlist with eight songs on it, and seven of those are in your library. You probably like this type of song, so Discover Weekly might recommend the one song that isn’t in your library.[32] This technique is called “collaborative filtering,” and it’s the same technique that Amazon uses to suggest items you might like based on your purchase history and the purchases of millions of other users.[33] Netflix’s movie suggestions, YouTube’s video suggestions, and Facebook’s friend suggestions also use collaborative filtering.[34]
