Broadcasting is the distribution of audio and/or video signals which transmit programs to an audience. The original term "broadcast" referred to the literal 'sowing of seeds' on farms, by scattering them over a wide field. It was first adopted by early radio engineers from the Midwestern United States to refer to the analogous dissemination of radio signals. Broadcasting forms a very large segment of the mass media. Broadcasting to a very narrow range of audience is called narrowcasting.
Internet television (otherwise known as Internet TV, Catch-up TV or Online TV) is television service distributed via the Internet. It has become very popular at the end of the first decade of the 21st century due to services such as the BBC iPlayer (in and limited to the United Kingdom) and Hulu (limited to the United States); see List of Internet television providers.
Internet television allows its users to choose the program or the TV show they want to watch from an archive of programs or from a channel directory. The 2 forms of viewing Internet television are streaming the content directly to a media player or simply downloading the program/show onto the users computer. With the "TV on Demand" market growing, these on demand websites or applications are a must have for major televison broadcasters. For example the BBC's iPlayer brings in users which stream more than One Million videos per week, with one of the BBC's headline shows "The Apprentice" taking over 3 - 5% of the UK's internet traffic due to people watching the first episode on iPlayer.
Every night the use of On Demand TV peaks at around 10pm, Most providers of the service provide several different formats and quality controls so that the service can be viewed on many different devices. Some services now offer a HD service along side their SD, streaming is the same but offers the quality of HD to the device being used, as long as it is using a HD screen. During Peak times the BBC's iPlayer sends out 12GB (Gigabytes) worth of information a second, around the same as sending out 20 DVDs content per second.Over the course of a month the iPlayer sends out 7 Petabytes of information which is the same as 11 Million Dvd's content. This wide use of on demand services is causing Internet Service Providers a great deal of issues.
Before 2006 any Catch-up services were mostly P2P (Peer to Peer), where users would download an application and data would be shared between the users rather than the service provider giving the now more commonly used steaming method. Now most service providers have moved away from the P2P idea and are now using the Streaming method. This is good for the service provider as in the old P2P system the distribution costs were high and the servers normaly couldn't handle the large amount of downloading and data transfer.