Television

Television (often abbreviated to TV, T.V., tv, or t.v.) is a common telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term "television" may also be used to refer specifically to a television set, programming or television transmission. The word is derived from mixed Latin and Greek roots, meaning "far sight."

Starting from the late 1940s, the television set has become a common household reception device found worldwide and It is now ubiquitous in most residential homes, particularly in the first world, as a source of entertainment and news. Since the 1970s, video recordings and later, digital playback systems such as DVDs, have extended its uses.

A television system may be made up of components, so a screen which lacks an internal tuner is called a monitor rather than a television. A television may be built to receive different broadcast or video formats such as HDTV.

Television was not invented by a single person, but by several individuals. The origins of what would become today's television system can be traced back to the discovery of the photoconductivity of the element selenium by Willoughby Smith in 1873.

Paul Nipkow proposed the first practical television principle based on a scanning disc in 1884, but the Nipkow principle had to wait until suitable amplifiers were developed before it became practical. All practical television systems use the fundamental idea of scanning an image to produce a time series signal representation. That representation is then transmitted to a device to reverse the scanning process. The final device, the television (or TV set), relies on the human eye to integrate the result into a coherent image.

Electromechanical techniques were developed from the 1900s into the 1920s, progressing from the transmission of still photographs, to live still duotone images, to moving duotone or silhouette images, with each step increasing the sensitivity and speed of the scanning photoelectric cell. John Logie Baird gave the world's first public demonstration of a working television system based on the Nipkow principle that transmitted live moving images with tone graduation (grayscale) on 26 January 1926 at his laboratory in London, and built a complete experimental broadcast system around his technology. Baird further demonstrated the world's first color television transmission on 3 July 1928. Other prominent developers of mechanical television included Charles Francis Jenkins, who demonstrated a primitive television system in 1923, Frank Conrad who demonstrated a movie-film-to-television converter at Westinghouse in 1928, and Frank Gray and Herbert E. Ives at Bell Labs who demonstrated wired long-distance television in 1927 and two-way television in 1930. Camarena invented the "Chromoscopic adapter for television equipment", an early color television transmission system. As it is written in the patent: The invention relates to the transmission and reception of colored pictures or images by wire or wireless. Even though the invention was not already adaptable to standard television equipment then in use; the invention was considered easy to adapt to any transmitter or receiver of black and white television equipment. He applied for this patent August 14, 1941 and obtained the patents for color television systems September 15, 1942 (U.S. Patent 2296019), 1960 and 1962.

Regular broadcast programming occurred in the United States, the United Kingdom, Germany, France, and the Soviet Union before World War II.

Regular network broadcasting began in the United States in 1946, and television became common in American homes by the middle 1950s. While North American over-the-air broadcasting was originally free of direct marginal cost to the consumer (i.e., cost in excess of acquisition and upkeep of the hardware) and broadcasters were compensated primarily by receipt of advertising revenue, increasingly United States television consumers obtain their programming by subscription to cable television systems or direct-to-home satellite transmissions. In the United Kingdom, France, and most of the rest of Europe, on the other hand, operators of television equipment must pay an annual license fee, which is usually used to fund (wholly or partly) the appropriate national public service broadcaster(s).