TV is a widely used telecommunication medium in the world.
Televisions were commercially available since 1930. Televisions has became one of the most used telecommunication system worldwidely. They are used commonly for broadcastig entertainment and news. From 1970's they have also been used to view video cassettes, laser discs, and dvd's from where people could watch prerecorded video or audio material.
DTV is recieving picture and sound by digital signals. As of late 2007 some countries started shutting off analog television, and starting widely digital television. First country to go "Digital" was Luxemburg,following Netherlands, Findland, Andorra, Sweden, Norway and Switzerland. In 2007, Belgium and Germany in 2008, and the U.S in 2009. In Japan they are scheduled to switch off analog TV by July 24 2011, Canada in August 31 2011 and China somewhere in 2015. U.K has diffrent time in diffrent parts of it, but it was claimed,that whole country will be digital in 2012.