A disc jockey (abbreviated D.J., DJ or deejay) is a person who mixes recorded music for an audience. Originally, "disc" (sometimes spelled "disk", although this is now uncommon) referred to phonograph records, not the later compact discs. Today, the term includes all forms of music playback, no matter the medium.
The title "DJ" is also commonly used by DJs in front of their real names or adopted pseudonyms as a title to denote their profession and the music they play.
There are several types of disc jockey. Radio DJs or radio personalities introduce and play music that is broadcast on AM, FM, shortwave, digital or internet radio stations. Club DJs select and play music in bars, nightclubs or discothèques, or at parties or raves, or even in stadiums. Mobile DJs travel with portable sound systems and play recorded music at a variety of events. Some mobile DJs also serve as the master of ceremonies or MC directing the attention of attendees, and maintaining a room-wide focus on what is included in the event's agenda. There are also many competitions that specialise in mixing, scratching or other kinds of techniques.
Other types of DJ use musical performance techniques that allow them to be categorized as performing musicians, depending on the situation. Hip hop DJs not only select and play music using multiple turntables to back up one or more MCs/rappers, but they also perform turntable scratching to create percussive sounds, and are also often songwriters and/or music producers who use turntablism and sampling to create backing instrumentals for new tracks. In reggae, the DJ (deejay) is a vocalist who raps, "toasts", or chats over pre-recorded rhythm tracks while the individual choosing and playing them is referred to as a selector.  Many electronica artists and producers who also work as DJs often perform music by combining turntablism with keyboards or live electronics. Electronica, hip-hop or reggae DJs also often collaborate and play live music with bands and musicians from several musical genres (rock, heavy metal, jazz or even classical music), using turntables and electronics as musical instruments. According to a 2012 study, there are approximately 1¼ million professional disc jockeys in the world.
Equipment and technique
Club DJ equipment may consist of:
- Sound recordings in a DJ's preferred medium (for example, vinyl records, CDs, computer media files, etc.)
- A combination of two devices (or only one, if playback is digital) to play sound recordings, for alternating back and forth to create a continuous playback of music (for example, record players, Compact Disc players, computer media players such as an MP3 player, etc.)
- A multiple sequencer which can mix MIDI tracks with Digital Audio
- A sound system for amplification or broadcasting of the recordings (for example, portable audio system, public address system) or a radio broadcasting system
- A DJ mixer, which is an (usually 2- or 4-channel) audio mixer usually equipped with a crossfader used to smoothly go from one song to another, using two or more playback devices;
- Headphones, or earphones used to listen to one recording while the other recording is being played to the audience, or to listen to both recordings simultaneously; and
- Optionally, a microphone, so that the DJ can introduce songs and speak to the audiences.
Other equipment could or can be added to the basic DJ setup (above), providing unique sound manipulations. Such devices include, but are not limited to:
- Electronic effects units such as delay, reverb, octave, equalizer, chorus, etc. Some club DJs use a subharmonic synthesizer effect which either doubles low frequencies with energy added an octave lower or synthesizes harmonics such that the impression of a very low bass sound is added to the mix.
- A computerised performance system, which can be used with vinyl emulation software to manipulate digital files on the computer in real time.
- Multi-stylus headshells, which allow a DJ to play different grooves of the same record at the same time.
- Special DJ digital controller hardware that can manipulate digital files on a PC or laptop.
- Samplers, sequencers, electronic musical keyboards (synthesizers), or drum machines.
- A Midi controller used to trigger different aspects of DJ software, such as Serato Scratch Live, VirtualDJ and Traktor.
Several techniques are used by DJs as a means to better mix and blend recorded music. These techniques primarily include the cueing, equalization and audio mixing of two or more sound sources. The complexity and frequency of special techniques depends largely on the setting in which a DJ is working. Radio DJs are less likely to focus on music-mixing procedures than club DJs, who rely on a smooth transition between songs using a range of techniques.
Club DJ turntable techniques include beatmatching, phrasing and slip-cueing to preserve energy on a dancefloor. Turntablism embodies the art of cutting, beat juggling, scratching, needle drops, phase shifting, back spinning and more to perform the transitions and overdubs of samples in a more creative manner (although turntablism is often considered a use of the turntable as a musical instrument rather than a tool for blending recorded music). Professional DJs may use harmonic mixing to choose songs that are in compatible musical keys.
Recent advances in technology in both DJ hardware and software can provide assisted or automatic completion of some traditional DJ techniques and skills. Examples include phrasing and beatmatching, which can be partially or completely automated by utilizing DJ software that performs automatic synchronization of sound recordings, a feature commonly labelled "sync". Most DJ mixers now include a beat-counter which analyzes the tempo of an incoming sound source and displays its tempo in beats per minute (BPM), which may assist with beatmatching analog sound sources.
In the past, being a DJ has largely been a self-taught craft but with the complexities of new technologies and the convergence with music production methods, there are a growing number of schools and organizations that offer instruction on the techniques. 
19th century to 1920s
In 1892, Emile Berliner began commercial production of his gramophone records, the first disc records to be offered to the public. In 1906, Reginald Fessenden transmitted the first audio radio broadcast in history also playing the first record, that of a contralto singing Handel's Largo from Xerxes.
The world's first radio disc jockey was Ray Newby, of Stockton, California. In 1909, at 16 years of age, Newby began regularly playing records on a small transmitter while a student at Herrold College of Engineering and Wireless, located in San Jose, California, under the authority of radio pioneer Charles "Doc" Herrold.
"We used popular records at that time, mainly Caruso records, because they were very good and loud; we needed a boost... we started on an experimental basis and then, because this is novel, we stayed on schedule continually without leaving the air at any time from that time on except for a very short time during World War I, when the government required us to remove the antenna... Most of our programming was records, I'll admit, but of course we gave out news as we could obtain it..."—Ray Newby, I've Got a Secret (1965)
By 1910, regular radio broadcasting had started to use "live" as well as prerecorded sound. In the early radio age, content typically included comedy, drama, news, music, and sports reporting. The on-air announcers and programmers would later be known as disc jockeys. In the 1920s, juke joints became popular as places for dancing and drinking to recorded jukebox music. In 1927, Christopher Stone became the first radio announcer and programmer in the United Kingdom, on the BBC radio station.
In 1935, American radio commentator Walter Winchell coined the term "disc jockey" (the combination of disc, referring to the disc records, and jockey, which is an operator of a machine) as a description of radio announcer Martin Block, the first announcer to become a star. While his audience was awaiting developments in the Lindbergh kidnapping, Block played records and created the illusion that he was broadcasting from a ballroom, with the nation’s top dance bands performing live. The show, which he called Make Believe Ballroom, was an instant hit. The term "disc jockey" appeared in print in Variety in 1941.
Prior to this, most music heard on radio was live; most radio stations had an orchestra or band on the payroll. The Federal Communications Commission also clearly favored live music, providing accelerated license approval to stations promising not to use any recordings for their first three years on the air. Many noted recording artists tried to keep their recorded works off the air by having their records labeled as not being legal for airplay. It took a Federal court ruling in 1940 to establish that a recording artist had no legal right to control the use of a record after it was sold.
In 1943, Jimmy Savile launched the world's first DJ dance party by playing jazz records in the upstairs function room of the Loyal Order of Ancient Shepherds in Otley, England. In 1947, he claims to have become the first DJ to use twin turntables for continuous play, and in 1958 became a radio DJ at Radio Luxembourg. Also in 1947, the Whiskey à Go-Go nightclub opened in Paris, France, considered to be the world's first commercial discothèque, or disco (deriving its name from the French word meaning a nightclub where the featured entertainment is recorded music rather than an on-stage band). Regine began playing on twin turntables there in 1953. Discos began appearing across Europe and the United States.
The postwar period coincided with the rise of the radio disc jockey as a celebrity separate from the radio station, also known as a "radio personality". In the days before station-controlled playlists, the DJ often followed their personal tastes in music selection. DJs also played a role in exposing rock and roll artists to large, national audiences. While at WERE (1300 AM) in Cleveland, Ohio, DJ Bill Randle was one of the first to introduce Elvis Presley to radio audiences in the northeastern U.S.
Notable U.S. radio disc jockeys of the period include Alan Freed, Wolfman Jack, Casey Kasem, and their British counterparts such as the BBC's Brian Matthew, and in the '60s Radio London's John Peel, and Radio Caroline's Tony Blackburn.
Freed is commonly referred to as the "father of rock and roll" due to his promotion of the music and his introduction of the phrase "rock and roll" on radio in the early 1950s. Freed also made a practice of presenting music by African-American artists rather than cover versions by white artists on his radio program. Freed's career ended when it was shown that he had accepted payola, a practice that was highly controversial at the time, resulting in his being fired from his job at WABC.
In the 1950s, American radio DJs would appear live at "sock hops" and "platter parties" and assume the role of a human jukebox. They would usually play 45-rpm records, featuring hit singles on one turntable while talking between songs. In some cases, a live drummer was hired to play beats between songs to maintain the dance floor. In 1955, Bob Casey, a well-known "sock hop" DJ, brought the two-turntable system to the U.S. Throughout the 1950s, payola continued to be a problem and one result of the payola scandal was tighter control of the music by station management. The Top 40 format emerged, where popular songs are played repeatedly.
In the late 1950s, sound systems, a new form of public entertainment, were developed in the ghettos of Kingston, Jamaica. Promoters, who called themselves DJs, would throw large parties in the streets that centered on the disc jockey, called the "selector," who played dance music from large, loud PA systems and bantered over the music with a boastful, rhythmic chanting style called "toasting". These parties quickly became profitable for the promoters, who would sell admission, food, and alcohol, leading to fierce competition between DJs for the biggest sound systems and newest records.
1960s and 1970s
In the mid-1960s, nightclubs and discothèques continued to grow in Europe and the United States. Specialized DJ equipment, such as Rudy Bozak's classic CMA-10-2DL mixer, began to appear on the market. In 1969, American club DJ Francis Grasso popularized beatmatching at New York's Sanctuary nightclub. Beatmatching is the technique of creating seamless transitions between records with matching beats, or tempos. Grasso also developed slip-cuing, the technique of holding a record still while the turntable is revolving underneath, releasing it at the desired moment to create a sudden transition from the previous record. (This technique had long been used in radio.)
By 1968, the number of dance clubs started to decline; most American clubs either closed or were transformed into clubs featuring live bands. Neighborhood block parties that were modelled after Jamaican sound systems gained popularity in Europe and in the boroughs of New York City.
In 1973, Jamaican-born DJ Kool Herc, widely regarded as the "father of hip-hop culture," performed at block parties in his Bronx neighborhood and developed a technique of mixing back and forth between two identical records to extend the rhythmic instrumental segment, or break. Turntablism, the art of using turntables not only to play music but to manipulate sound and create original music, began to develop.
In 1974, Technics released the first SL-1200 turntable, which evolved into the SL-1200 MK2 in 1979—which, as of the early-2010s, remains an industry standard for DJing. In 1974, German electronic music band Kraftwerk released the 22-minute song "Autobahn," which takes up the entire first side of that LP. Years later, Kraftwerk would become a significant influence on hip-hop artists such as Afrika Bambaataa and house music pioneer Frankie Knuckles. During the mid-1970s, Hip-hop music and culture began to emerge, originating among urban African Americans and Latinos in New York City. The four main elements of Hip Hop culture are graffiti, DJing, breakdancing, and MCing (rapping).
In the mid-1970s, the soul-funk blend of dance pop known as disco took off in the mainstream pop charts in the United States and Europe, causing discothèques to experience a rebirth. Unlike many late-1960s clubs, which featured live bands, discothèques used the DJ's selection and mixing of records as the entertainment. In 1975, record pools began, providing disc jockeys access to newer music from the industry in an efficient method.
In 1975, hip-hop DJ Grand Wizard Theodore invented the scratching technique by accident. In 1976, American DJ, editor, and producer Walter Gibbons remixed "Ten Percent" by Double Exposure, one of the earliest commercially released 12″ singles (aka "maxi-single"). In 1979, the Sugar Hill Gang released "Rapper's Delight", the first hip-hop record to become a hit. It was also the first real breakthrough for sampling, as the bassline of Chic's "Good Times" laid the foundation for the song.
In 1977, Saratoga Springs, NY disc jockey Tom L. Lewis introduced the Disco Bible (later renamed Disco Beats), which published hit disco songs listed by beats per minute (tempo), as well as by either artist or song title. Billboard ran an article on the new publication, and it went national relatively quickly. The list made it easier for beginning DJs to learn how to create seamless transitions between songs without dancers having to change their rhythm on the dance floor. Today, DJs can find the beats per minute of songs in the BPM List.
In 1981, the cable television network MTV was launched, originally devoted to music videos, especially popular rock music. The term "video jockey", or VJ, was used to describe the fresh-faced youth who introduced the music videos. In 1982, the demise of disco in the mainstream by the summer of 1982 forced many nightclubs to either close or change entertainment styles, such as by providing MTV-style video dancing or live bands. Released in 1982, the song "Planet Rock" by DJ Afrika Bambaataa was the first hip-hop song to feature synthesizers. The song melded electro hip-hop beats influenced by Yellow Magic Orchestra with the melody from Kraftwerk's "Trans-Europe Express." In 1982, the Compact Disc reached the public market in Asia, and early the following year in other markets. This event is often seen as the "Big Bang" of the digital audio revolution.
In the early 1980s, NYC disco DJ Larry Levan, known for his eclectic mixes, gained a cult following, and the Paradise Garage, the nightclub at which he spun, became the prototype for the modern dance club where the music and the DJ were showcased. Around the same time, the disco-influenced electronic style of dance music called house music emerged in Chicago. The name was derived from the Warehouse Club in Chicago, where resident DJ Frankie Knuckles mixed old disco classics and Eurosynth pop. House music is essentially disco music with electronic drum machine beats. The common element of most house music is a 4/4 beat generated by a drum machine or other electronic means (such as a sampler), together with a solid (usually also electronically generated) synth bassline. In 1983, Jesse Saunders released what some consider the first house music track, "On & On." The mid-1980s also saw the emergence of New York Garage, a house music hybrid that was inspired by Levan's style and sometimes eschewed the accentuated high-hats of the Chicago house sound.
During the mid-1980s, techno music emerged from the Detroit club scene. Being geographically located between Chicago and New York, Detroit techno artists combined elements of Chicago house and New York garage along with European imports. Techno distanced itself from disco's roots by becoming almost purely electronic with synthesized beats. In 1985, the Winter Music Conference started in Fort Lauderdale Florida and became the premier electronic music conference for dance music disc jockeys.
In 1985, TRAX Dance Music Guide was launched by American Record Pool in Beverly Hills. It was the first national DJ-published music magazine, created on the Macintosh computer using extensive music market research and early desktop publishing tools. In 1986, "Walk This Way", a rap/rock collaboration by Run DMC and Aerosmith, became the first hip-hop song to reach the Top 10 on the Billboard Hot 100. This song was the first exposure of hip-hop music, as well as the concept of the disc jockey as band member and artist, to many mainstream audiences. In 1988, DJ Times magazine was first published. It was the first US-based magazine specifically geared toward the professional mobile and club DJ.
During the early 1990s, the rave scene built on the acid house scene. The rave scene changed dance music, the image of DJs, and the nature of promoting. The innovative marketing surrounding the rave scene created the first superstar DJs who established marketable "brands" around their names and sound. Some of these celebrity DJs toured around the world and were able to branch out into other music-related activities. During the early 1990s, the Compact Disc surpassed the gramophone record in popularity, but gramophone records continued to be made (although in very limited quantities) into the 21st century—particularly for club DJs and for local acts recording on small regional labels.
In 1991, Mobile Beat magazine, geared specifically toward mobile DJs, began publishing. In 1992, MPEG which stands for the Moving Picture Experts Group, released The MPEG-1 standard, designed to produce reasonable sound at low bit rates. The lossy compression scheme MPEG-1 Layer-3, popularly known as MP3, later revolutionized the digital music domain. In 1993, the first internet "radio station", Internet Talk Radio, was developed by Carl Malamud. Because the audio was relayed over the internet, it was possible to access internet radio stations from anywhere in the world. This made it a popular service for both amateur and professional disc jockeys operating from a personal computer.
In 1998, the first MP3 digital audio player was released, the Eiger Labs MPMan F10. Final Scratch debuted at the BE Developer Conference, marking the first digital DJ system to allow DJs control of MP3 files through special time-coded vinyl records or CDs. While it would take sometime for this novel concept to catch on with the "die hard Vinyl DJs", This would soon become the first step in the new Digital DJ revolution. Manufacturers joined with computer DJing pioneers to offer professional endorsements, the first being Professor Jam (aka William P. Rader), who went on to develop the industry's first dedicated computer DJ convention and learning program, the "CPS (Computerized Performance System) DJ Summit", to help spread the word about the advantages of this emerging technology.
In 1999, Shawn Fanning released Napster, the first of the massively popular peer-to-peer file sharing systems. During this period, the AVLA (Audio Video Licensing Agency) of Canada announced an MP3 DJing license, administered by the Canadian Recording Industry Association. This meant that DJs could apply for a license giving them the right to perform publicly using music stored on a hard drive, instead of having to cart their whole CD collections around to their gigs.
At the start of the new century, the introduction of advances in technology made it possible for new sounds to be developed. The introduction of the Pioneer SVM-1000 Audio and Video Mixer and other high tech digital sound mixers made a whole new culture of disco DJ integration. The appearance of games like DJ Hero gave birth to the scratch-off contests. The proliferation of Internet technologies have also created a culture of disc jockey enthusiast groups. DJ battles imitating the events on the game gave the DJ industry a more competitive phase. The DJ industry has become increasingly about the atmosphere that goes along with a performance. Now not only does the DJ show deal with music and mixing but also lights and effect go along with it.
DJs in film
- Berlin Calling — a German fiction film about DJ and producer Ickarus (Paul Kalkbrenner) struggling with drug abuse
- Speaking in Code — an American documentary film about techno artists Modeselektor, Wighnomy Brothers, Philip Sherburne, Monolake and David Day
- Kvadrat — a French / Russian documentary film about the realities of techno DJing, using the example of DJ Andrey Pushkarev
- Digital DJ licensing
- Disc or disk (spelling)
- List of club DJs
- Live PA
- Record collecting
- Seoul World DJ Festival
- Stage lighting
- Last Night a DJ Saved My Life, written by Bill Brewster and Frank Broughton, Published by Headline, updated 2006
-  Maintaining the Focus
- The Official Global DJ Rankings
- "Harmonic mixing: The Basics". Retrieved 29 December 2013.
- "DJ Mixes Remixes". Retrieved 29 December 2013.
- Brewster, Bill (2006). Last Night a DJ Saved my Life. Headline. p. 29. ISBN 0-7553-1398-4.
- Ray Newby appearance on CBS' I've Got a Secret, 27 September 1965. Secret listed as: "'I was the world's first radio disc jockey' (in 1909)." Rebroadcast on the Game Show Network on 22 May 2008.
- Bay Area Radio Museum. "Doc Herrold and Ray Newby". Retrieved 21 May 2008.
- Fisher, Marc. Something in the Air. Random House. p. 13. ISBN 978-0-375-50907-0.
- Roddy, Bill. "NBC's Radio City, San Francisco". Roddy, Bill. Retrieved 26 April 2010.
- Samuels, Rich. "The NBC Chicago Orchestra". Samuels, Rich. Retrieved 26 April 2010.
- "Keep Your Big Mouth Shut ..Disc Jockeys Learn To Toil And Spin". Eugene Register-Guard. June 23, 1955. Retrieved 29 December 2013.
- "Big Day Belongs To The Local Hero". The Glasgow Herald. September 12, 1983. Retrieved 29 December 2013.
- Curtis, James M. (1987). Rock eras: interpretations of music and society, 1954-1984. Popular Press. ISBN 978-0-87972-369-9.
- Richard Sisson; Christian K. Zacher; Andrew Robert Lee Cayton (2007). The American Midwest: an interpretive encyclopedia. Indiana University Press. pp. 636–. ISBN 978-0-253-34886-9. Retrieved 13 October 2011.
- Christopher H. Sterling; Michael C. Keith; Communications Museum of Broadcast (2004). Encyclopedia of radio. Taylor & Francis. pp. 375–. ISBN 978-1-57958-249-4. Retrieved 13 October 2011.
- Glenn C. Altschuler (16 July 2003). All shook up: how rock 'n' roll changed America. Oxford University Press. pp. 152–. ISBN 978-0-19-513943-3. Retrieved 13 October 2011.
- "Turntable Teaching .Berklee College Offers Course On Scratching.". Sun Journal. Feb 18, 2004. Retrieved 29 December 2013.
- Assef, Claudia (2000). Todo DJ Já Sambou: A História do Disc-Jóquei no Brasil. São Paulo: Conrad Editora do Brasil. ISBN 85-87193-94-5.
- Brewster, Bill, and Frank Broughton (2000). Last Night a DJ Saved My Life: The History of the Disc Jockey. New York: Grove Press. ISBN 0-8021-3688-5 (North American edition). London: Headline. ISBN 0-7472-6230-6 (UK edition).
- Broughton, Frank, and Bill Brewster. How to DJ Right: The Art and Science of Playing Records. New York: Grove Press, 2003.
- Graudins, Charles A. How to Be a DJ. Boston: Course Technology PTR, 2004.
- Lawrence, Tim (2004). Love Saves the Day: A History of American Dance Music Culture, 1970–1979 . Duke University Press. ISBN 0-8223-3198-5.
- Miller, Paul D. aka DJ Spooky, Sound Unbound: Writings on DJ Culture and Electronic Music, MIT Press 2008. ISBN 0-262-63363-9 ISBN 978-0-262-63363-5.
- Poschardt, Ulf (1998). DJ Culture. London: Quartet Books. ISBN 0-7043-8098-6.
- Zemon, Stacy. The Mobile DJ Handbook: How to Start & Run a Profitable Mobile Disc Jockey Service, Second Edition. St. Louis: Focal Press, 2002
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