Spotify is the largest on-demand music services in the world and has 299 million monthly users, including 138 million paying subscribers. One of the exciting features of the Spotify is Discover Weekly. It's a custom mixtape of 30 songs they've never listened to before but will probably love, and it's pretty much magic. Songza used to curate playlists manually in the early 2000s which was not able to fulfil the music needs of the consumers as it was developed as on specific interest of the curator. Pandora used tagging the songs manually with attributes like'folk', 'rock' and curating playlist with similar tags using the code. Collaborative filtering: It works by comparing people with similar tastes.