Digital Rights Management, short for DRM, which is a system for authorizing the viewing or playback of copyrighted material on a user’s computer or digital music player. DRM has centered around copyrighted music, with Apple’s FairPlay and Microsoft’s Windows Digital Rights Manager being the two predominant DRM systems. As broadband Internet and more highly compressed video formats take hold, the focus of DRM broadens to video content.

If you have music files with DRM protection want to remove. Here is a video from YouTube will show you how to remove DRM protection from music