A rootkit is a piece of software that changes the way that the operating system works. Sony added a rootkit to its music CDs to implement digital rights management (DRM) A well designed rootkit hides itself effectively by messing with the computer operating system. Sony quickly removed its rootkit from its CDs and issued apologies for the damage caused by the software. The need for DRM is clear, not just for music but for a wide variety of digital information, but there is a small army of hackers that work at circumventing any DRM scheme that anyone tries to implement.”]
Source: https://www.csoonline.com/article/2119004/the-rootkit-problem.html