This Recommendation gives an overview of Internet Protocol television (IPTV) terminal devices and end systems. It also describes the general architecture and functional components of an IPTV terminal device, providing a high-level description of functionality of terminal devices for IPTV services. It provides the definitions of terminal device and end system, the location of terminal devices and end systems within the overall architecture of IPTV, examples of IPTV services, an abstract description of the terminal device architecture, and descriptions of other Recommendations that discuss IPTV terminal devices.