Television
Television (TV) is a telecommunication medium for transmitting moving images and sound. Additionally, the term can refer to a physical television set, rather than the medium of transmission. Television is a mass medium for advertising, entertainment, news, and sports. The medium is capable of more than "radio broadcasting", which refers to an audio signal sent to radio receivers.
This article is about the telecommunication medium. For the appliance itself, see Television set. For other uses, see Television (disambiguation).
Television became available in crude experimental forms in the 1920s, but only after several years of further development was the new technology marketed to consumers. After World War II, an improved form of black-and-white television broadcasting became popular in the United Kingdom and the United States, and television sets became commonplace in homes, businesses, and institutions. During the 1950s, television was the primary medium for influencing public opinion.[1] In the mid-1960s, color broadcasting was introduced in the U.S. and most other developed countries.
The availability of various types of archival storage media such as Betamax and VHS tapes, LaserDiscs, high-capacity hard disk drives, CDs, DVDs, flash drives, high-definition HD DVDs and Blu-ray Discs, and cloud digital video recorders has enabled viewers to watch pre-recorded material—such as movies—at home on their own time schedule. For many reasons, especially the convenience of remote retrieval, the storage of television and video programming now also occurs on the cloud (such as the video-on-demand service by Netflix). At the beginning of the 2010s, digital television transmissions greatly increased in popularity. Another development was the move from standard-definition television (SDTV) (576i, with 576 interlaced lines of resolution and 480i) to high-definition television (HDTV), which provides a resolution that is substantially higher. HDTV may be transmitted in different formats: 1080p, 1080i and 720p. Since 2010, with the invention of smart television, Internet television has increased the availability of television programs and movies via the Internet through streaming video services such as Netflix, Amazon Prime Video, iPlayer and Hulu.
In 2013, 79% of the world's households owned a television set.[2] The replacement of earlier cathode-ray tube (CRT) screen displays with compact, energy-efficient, flat-panel alternative technologies such as LCDs (both fluorescent-backlit and LED), OLED displays, and plasma displays was a hardware revolution that began with computer monitors in the late 1990s. Most television sets sold in the 2000s were flat-panel, mainly LEDs. Major manufacturers announced the discontinuation of CRT, Digital Light Processing (DLP), plasma, and even fluorescent-backlit LCDs by the mid-2010s.[3][4] LEDs are being gradually replaced by OLEDs.[5] Also, major manufacturers have started increasingly producing smart TVs in the mid-2010s.[6][7][8] Smart TVs with integrated Internet and Web 2.0 functions became the dominant form of television by the late 2010s.[9]
Television signals were initially distributed only as terrestrial television using high-powered radio-frequency television transmitters to broadcast the signal to individual television receivers. Alternatively television signals are distributed by coaxial cable or optical fiber, satellite systems and, since the 2000s via the Internet. Until the early 2000s, these were transmitted as analog signals, but a transition to digital television was expected to be completed worldwide by the late 2010s. A standard television set consists of multiple internal electronic circuits, including a tuner for receiving and decoding broadcast signals. A visual display device that lacks a tuner is correctly called a video monitor rather than a television.
Etymology
The word television comes from Ancient Greek τῆλε (tele) 'far', and Latin visio 'sight'. The first documented usage of the term dates back to 1900, when the Russian scientist Constantin Perskyi used it in a paper that he presented in French at the first International Congress of Electricity, which ran from 18 to 25 August 1900 during the International World Fair in Paris.
The anglicised version of the term is first attested in 1907, when it was still "...a theoretical system to transmit moving images over telegraph or telephone wires".[10] It was "...formed in English or borrowed from French télévision."[10] In the 19th century and early 20th century, other "...proposals for the name of a then-hypothetical technology for sending pictures over distance were telephote (1880) and televista (1904)."[10]
The abbreviation TV is from 1948. The use of the term to mean "a television set" dates from 1941.[10] The use of the term to mean "television as a medium" dates from 1927.[10]
The term telly is more common in the UK. The slang term "the tube" or the "boob tube" derives from the bulky cathode-ray tube used on most TVs until the advent of flat-screen TVs. Another slang term for the TV is "idiot box".[11]
Negative impacts
Children, especially those aged 5 or younger, are at risk of injury from falling televisions.[249] A CRT-style television that falls on a child will, because of its weight, hit with the equivalent force of falling multiple stories from a building.[250] Newer flat-screen televisions are "top-heavy and have narrow bases", which means that a small child can easily pull one over.[251] As of 2015, TV tip-overs were responsible for more than 10,000 injuries per year to children in the United States, at a cost of more than US$8 million per year (equivalent to US$10.28 million per year in 2023) in emergency care.[249][251]
A 2017 study in The Journal of Human Resources, found that exposure to cable television reduced cognitive ability and high school graduation rates for boys. This effect was stronger for boys from more educated families. The article suggests a mechanism where light television entertainment crowds out more cognitively stimulating activities.[252]
With high lead content in CRTs and the rapid diffusion of new flat-panel display technologies, some of which (LCDs) use lamps which contain mercury, there is growing concern about electronic waste from discarded televisions. Related occupational health concerns exist, as well, for disassemblers removing copper wiring and other materials from CRTs. Further environmental concerns related to television design and use relate to the devices' increasing electrical energy requirements.[253]