Pandora Internet Radio (also known as Pandora Radio or simply Pandora) is an automated music recommendation service and "custodian" of the Music Genome Project. The service, operated by Pandora Media, Inc., is only available in the United States, Australia and New Zealand. The service plays musical selections of a certain genre based on the user's artist selection. The user then provides positive or negative feedback for songs chosen by the service, which are taken into account when Pandora selects future songs.
While listening, users are offered the ability to buy the songs or albums at various online retailers. Over 400 different musical attributes are considered when selecting the next song. These 400 attributes are combined into larger groups called focus traits. There are 2,000 focus traits. Examples of these are rhythm syncopation, key tonality, vocal harmonies, and displayed instrumental proficiency.