Internet Protocol television is a system through which television services are delivered using the Internet protocol suite over a packet-switched network such as a LAN or the Internet, instead of being delivered through traditional terrestrial, satellite signal, and cable television formats. Unlike downloaded media, IPTV offers the ability to stream the media in smaller batches, directly from the source. As a result, a client media player can begin playing the data (such as a movie) before the entire file has been transmitted. This is known as streaming media.
Services may be classified into three main groups:
Live television, with or without interactivity related to the current TV show;
Time-shifted television: catch-up TV (replays a TV show that was broadcast hours or days ago), start-over TV (replays the current TV show from its beginning);
Video on demand (VOD): browse a catalogue of videos, not related to TV programming.
IPTV is distinguished from Internet television by its ongoing standardisation process (e.g., European Telecommunications Standards Institute) and preferential deployment scenarios in subscriber-based telecommunications networks with high-speed access channels into end-user premises via set-top boxes or other customer-premises equipment.
Historically, many different definitions of IPTV have appeared, including elementary streams over IP networks, transport streams over IP networks and a number of proprietary systems.
One official definition approved by the International Telecommunication Union focus group on IPTV (ITU-T FG IPTV) is:
IPTV is defined as multimedia services such as television/video/audio/text/graphics/data delivered over IP based networks managed to provide the required level of quality of service and experience, security, interactivity and reliability.
The number of global IPTV subscribers was expected to grow from 28 million in 2009 to 83 million in 2013. Europe and Asia are the leading territories in terms of the over-all number of subscribers. But in terms of service revenues, Europe and North America generate a larger share of global revenue, due to very low average revenue per user (ARPU) in China and India, the fastest growing (and ultimately, the biggest markets) is Asia. The global IPTV market revenues are forecast to grow from US$12 billion in 2009 to US$38 billion in 2013.