DRM stands for “Digital Rights Management.” It is the technology that controls your access to copyrighted works such as movies, music, literature and software. The product files are encrypted so that you can only use them on authorized devices. For example, if you have downloaded music onto your PC, and want to access it with your smart phone, you may need to enter a username and password in order to be authorized to do so. Additionally, there may be a maximum number of devices from which you can access your purchased files.
While it is convenient to carry around your media on your mobile device, keep in mind that you still need to adhere to licensing agreements. Amazon MP3 Music Service, for example, specifies that you must only use their digital content for “your personal, non-commercial, entertainment use.” Apple iTunes authorizes you to use iTunes Products on five iTunes-authorized devices at any time, except for content rentals which may only be used on one device at a time. The exception is iTunes Plus Products, which do not do not contain security technology that limits your usage. According to Apple, “you can copy, store, and burn iTunes Plus Products as reasonably necessary for personal, noncommercial use.”