This chapter discusses technologies and standards related to digital rights management (DRM). Firstly, it presents DRM systems that are multimedia information management systems that take into account digital rights and protection. These systems enable the controlled distribution and use of multimedia content through the digital value chain. Then, this chapter presents current initiatives, standard and proprietary, that specify a DRM system. It focuses in the MPEG-21 standard initiative, mainly in the parts of this standard that normatively specify the different pieces and formats needed by a complete DRM system. Finally, this chapter presents one of the key components of DRM systems, rights expression languages (RELs) that have been defined to express content usage rules.