Television is a telecommunication system for broadcasting and receiving moving pictures and sound over a distance. The term has come to refer to all the aspects of television from the television set to the programming and transmission. The word is derived from mixed Latin and Greek roots, meaning "far seeing" (Greek τῆλε "tele," meaning far, and Latin "visus," meaning seeing).
History of television
The origins of what would become today's television system can be traced back as far as the discovery of the photoconductivity of the element selenium by Willoughby Smith in 1873 and the invention of a scanning disk by Paul Nipkow in 1884. 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, relies on the human eye to integrate the result into a coherent image.
While electromechanical techniques were developed prior to World War II, most notably by Charles Francis Jenkins and John Logie Baird, completely electronic television systems relied on the inventions of Philo Taylor Farnsworth, Vladimir Zworykin and others to produce a system suitable for mass distribution of television programming. Commercial broadcast programming, following years of experimental broadcasts seen only in a few specially-equipped homes, occurred in both the United States and the United Kingdom before World War II.
The first television broadcasts with a modern level of definition (more than 240 lines) were made in England in 1936. So-called "System A" used 405 lines. Television did not become common in United States homes until 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, on the other hand, the owner of each television must pay a licence fee annually which is used to support the British Broadcasting Corporation.