The digital rights management (DRM) system from Apple that encodes copy protected TV shows and movies purchased on the iTunes online music store. Songs and music videos were previously protected with FairPlay, but it was removed in 2009, and users could upgrade to the non-protected versions of their purchase for a fee. The revised non-protected music policy was officially called iTunes Plus. Podcasts and iTunes U were never FairPlay protected, and in Japan, all content is protected.
Computers Must Be Authorized
FairPlay works by generating random encryption keys for each title purchased and storing the keys in the user's computer and iDevice. The content can be played on any number of iPods, iPhones and iPads; however, playing directly on the computer in iTunes is limited to five machines. The five computers must be identified and authorized, and a change to other machines if the user is at the limit requires de-authorizing the ones no longer in the mix. Music titles can be converted to a regular audio CD track without limit, but if used in an iTunes playlist, the five-computer limit applies. See AAC
and iTunes U