Pandora is an automated music recommendation (recommender system) service and custodian of the Music Genome Project. Users enter a song or artist that they enjoy, and the service responds by playing selections that are musically similar. Users provide feedback on approval or disapproval of individual songs, which Pandora takes into account for future selections.

While listening, users are offered the ability to buy the songs or albums at various online retailers. Over 400 different musical attributes (List of Music Genome Project 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.

The Pandora media player is based on OpenLaszlo. Pandora can also be accessed through many stand-alone players such as Frontier Silicon-based connected audio systems, Slim Devices and Sonos product(s). On July 11, 2008, Pandora launched a mobile version of their software for the Apple iPhone and iPod Touch through the iTunes App Store. Pandora is also available for Android (Android (operating system)) phones (such as the T-Mobile G1), BlackBerry platforms, WebOS (used on the Palm Pre), and Windows Mobile devices. Pandora was the provider for MSN Radio until MSN discontinued their internet radio service on June 18, 2008.

The service has two subscription plans: a free subscription supported by advertisements, and a fee-based subscription without ads. A free account user may reach the streaming limit of 40 hours per month, and continue unlimited streaming by paying $0.99. There are also advertisements in "Pandora Mobile" for mobile phones and the "Pandora in The Home" computer appliance.

As of March 2010, Pandora had 700,000 tracks in its library and 48 million users who listened for 11.6 hours per month on average.