Hardware-based DRM: The content is encrypted using a hardware key and can only be read on a specific computer. The main disadvantage of hardware-based DRM is that it is not compatible with all devices. For example, iTunes can only read the iTunes protected content on Apple computers. Software-based DRM: The content is encrypted using a software key and can only be read on devices with specific software compatibilities. The advantage of software-based DRM is that it is compatible with all the devices supported via software.