Controlling Distribution: Digital rights management (DRM) software [orange] plays its role when, say, a song, is to be bought and paid for. The software encodes content and copy-protects it with encryption [blue cylinder]. The song then moves to a media server, from which it can be ordered (step 1). A plug-in is downloaded, if needed (1a). Payment is authorized (2), as in a credit card transaction or a valid subscription is honored. Finally, a digital key to unlock the media's copy protection is delivered (3) so the song can be played.