Person who plays recorded music for an audience
A disc jockey, more commonly abbreviated as DJ, is a person who plays recorded music for an audience. Types of DJs include radio DJs (who host programs on music radio stations), club DJs (who work at nightclubs or music festivals), mobile DJs (who are hired to work at public and private events such as weddings, parties, or festivals), and turntablists (who use record players, usually turntables, to manipulate sounds on phonograph records). Originally, the "disc" in "disc jockey" referred to shellac and later vinyl records, but nowadays DJ is used as an all-encompassing term to also describe persons who mix music from other recording media such as cassettes, CDs or digital audio files on a CDJ, controller, or even a laptop. DJs may adopt the title "DJ" in front of their real names, adopted pseudonyms, or stage names.
DJs commonly use audio equipment that can play at least two sources of recorded music simultaneously. This enables them to blend tracks together to create transitions between recordings and develop unique mixes of songs. This can involve aligning the beats of the music sources so their rhythms and tempos do not clash when played together and enable a smooth transition from one song to another. DJs often use specialized DJ mixers, small audio mixers with crossfader and cue functions to blend or transition from one song to another. Mixers are also used to pre-listen to sources of recorded music in headphones and adjust upcoming tracks to mix with currently playing music. DJ software can be used with a DJ controller device to mix audio files on a computer instead of a console mixer. DJs may also use a microphone to speak to the audience; effects units such as reverb to create sound effects and electronic musical instruments such as drum machines and synthesizers.
List of popular DJs.
Some of the most popular DJs are Skrillex, David Guetta, Porter Robinson, deadmau5, Avicii, Calvin Harris, Martin Garrix, Marshmello, Zedd, Alan Walker, Eric Prydz, DJ Snake, R3HAB, Timmy Trumpet, Tiësto, Steve Aoki, Diplo, Nicky Romero, Lost Frequencies, Daft Punk.
Etymology.
The term "disc jockey" was ostensibly coined by radio gossip commentator Walter Winchell in 1935 to describe the radio work of Martin Block. The phrase first appeared in print in a 1941 "Variety" magazine. Originally, the word "disc" in "disc jockey" referred to phonograph or gramophone records and was used to describe radio personalities who introduced them on the air.
Role.
"DJ" is used as an all-encompassing term to describe someone who mixes recorded music from any source, including vinyl records, cassettes, CDs, or digital audio files stored on USB stick or laptop. DJs typically perform for a live audience in a nightclub or dance club or a TV, radio broadcast audience, or an online radio audience. DJs also create mixes, remixes and tracks that are recorded for later sale and distribution. In hip hop music, DJs may create beats, using percussion breaks, basslines and other musical content sampled from pre-existing records. In hip hop, rappers and MCs use these beats to rap over. Some DJs adopt the title "DJ" as part of their names (e.g., DJ Jazzy Jeff, DJ Qbert, DJ Shadow and DJ Yoda). Professional DJs often specialize in a specific genre of music, such as techno, house or hip hop music. DJs typically have extensive knowledge about the music they specialize in. Many DJs are avid music collectors of vintage, rare or obscure tracks and records.
Types.
Club DJs.
Club DJs, commonly referred to as DJs in general, play music at musical events, such as parties at music venues or bars, clubs, music festivals, corporate and private events. Typically, club DJs mix music recordings from two or more sources using different mixing techniques to produce a non-stopping flow of music. Mixing began with hip hop in the 1970s and would subsequently expand to other genres in especially (but not exclusively) dance music. 
One key technique used for seamlessly transitioning from one song to another is beatmatching. A DJ who mostly plays and mixes one specific music genre is often given the title of that genre; for example, a DJ who plays hip hop music is called a hip hop DJ, a DJ who plays house music is a house DJ, a DJ who plays techno is called a techno DJ, and so on.
The quality of a DJ performance (often called a DJ mix or DJ set) consists of two main features: technical skills, or how well the DJ can operate the equipment and produce smooth transitions between two or more recordings and a playlist; and the ability of a DJ to select the most suitable recordings, also known as "reading the crowd".
Hip hop DJs.
DJ Kool Herc, Grandmaster Flash, and Afrika Bambaataa were members of a block party at South Bronx from 1973 onwards. Kool Herc played records such as James Brown's "Give It Up or Turnit a Loose", Jimmy Castor's "It's Just Begun", Booker T. &amp; the M.G.'s' "Melting Pot", Incredible Bongo Band's "Bongo Rock" and "Apache", and UK rock band Babe Ruth's "The Mexican". With Bronx clubs struggling with street gangs, uptown DJs catering to an older disco crowd with different aspirations, and commercial radio also catering to a demographic distinct from teenagers in the Bronx, Herc's parties had a ready-made audience.
DJ Kool Herc developed the style that was the blueprint for hip hop music. Herc used the record to focus on a short, heavily percussive part in it: the "break". Since this part of the record was the one the dancers liked best, Herc isolated the break and prolonged it by changing between two record players. As one record reached the end of the break, he cued a second record back to the beginning of the break, which allowed him to extend a relatively short section of music into a "five-minute loop of fury". This innovation had its roots in what Herc called "The Merry-Go-Round", a technique by which the DJ switched from break to break at the height of the party. This technique is specifically called "The Merry-Go-Round" because according to Herc, it takes one "back and forth with no slack."
Radio DJs.
Radio DJs or radio personalities introduce and play music broadcasts on AM, FM, digital or Internet radio stations.
Dancehall/reggae deejays.
In Jamaican music, a deejay (DJ) is a reggae or dancehall musician who sings and "toasts" (recites poetry) to an instrumental riddim. Deejays are not to be confused with DJs from other music genres like hip hop, where they select and play music. Dancehall/reggae DJs who select riddims to play are called selectors. Deejays whose style is nearer to singing are sometimes called singjays.
The term deejay originated in the 1960s and 1970s when performers such as U-Roy and King Stitt toasted over the instrumental (dub music) versions of popular records. These versions were often released on the flip side to the song's 45 record. This gave the deejays the chance to create on-the-fly lyrics to the music. Big Youth, and I-Roy were famous deejays in Jamaica.
Turntablists.
Turntablists, also called battle DJs, use turntables and DJ mixer to manipulate recorded sounds to produce new music. In essence, they use DJ equipment as a musical instrument. Perhaps the best-known turntablist technique is scratching. Turntablists often participate in DJ contests like DMC World DJ Championships and Red Bull 3Style.
Residents.
A resident DJ performs at a venue on a regular basis or permanently. They would perform regularly (typically under an agreement) in a particular discotheque, a particular club, a particular event, or a particular broadcasting station. Residents have a decisive influence on the club or a series of events. Per agreement with the management or company, the DJ would have to perform under agreed times and dates. Typically, DJs perform as residents for two or three times in a week, for example, on Friday and Saturday. DJs who make a steady income from a venue are also considered resident DJs.
Examples for resident DJs are:
Women DJs.
In Western popular music, even though there are relatively few women DJs and turntablists, women musicians have achieved great success in singing and songwriting roles, however, they are given much less representation than men DJs. Part of this may stem from a generally low percentage of women in audio technology-related jobs. A 2013 "Sound on Sound" article by Rosina Ncube stated that there are "... few women in record production and sound engineering." Ncube states that "[n]inety-five percent of music producers are male, and although there are women producers achieving great things in music, they are less well-known than their counterparts." The vast majority of students in music technology programs are male. In hip hop music, the low percentage of women DJs and turntablists may stem from the overall men's domination of the entire hip hop music industry. Most of the top rappers, MCs, DJs, record producers and music executives are men. There are a small number of high-profile women, but they are rare. 
In 2007, Mark Katz's article "Men, Women, and Turntables: Gender and the DJ Battle", stated that "very few women [do turntablism] battle[s]; the matter has been a topic of conversation among hip-hop DJs for years." In 2010, Rebekah Farrugia said "the male-centricity of electronic dance music (EDM) culture" contributes to "a marginalisation of women in these [EDM] spaces." While turntablism and broader DJ practices should not be conflated, Katz suggests use or lack of use of the turntable broadly by women across genres and disciplines is impacted upon by what he defines as "male technophilia". Historian Ruth Oldenziel concurs in her writing on engineering with this idea of socialization as a central factor in the lack of engagement with technology. She says:an exclusive focus on women's supposed failure to enter the field – is insufficient for understanding how our stereotypical notions have come into being; it tends to put the burden of proof entirely on women and to [unreasonably] blame them for their supposedly inadequate socialization, their lack of aspiration, and their want of masculine values. An equally challenging question is why and how boys have come to love things technical, how boys have historically been socialized as technophiles.
Lucy Green has focused on gender in relation to musical performers and creators, and specifically on educational frameworks as they relate to both. She suggests that women's alienation from "areas that have a strong technological tendency such as DJing, sound engineering and producing" are "not necessarily about their dislike of these instruments but relates to the interrupting effect of their dominantly masculine delineations". Despite this, women and girls do increasingly engage in turntable and DJ practices, individually and collectively, and "carve out spaces for themselves in EDM and DJ Culture". A 2015 article cited a number of prominent women DJs: Hannah Wants, Ellen Allien, Miss Kittin, Monika Kruse, Nicole Moudaber, B.Traits, Magda, Nina Kraviz, Nervo, and Annie Mac. Two years later, another article brings out a list with world-famous women DJs including Nastia, tINY, Nora En Pure, Anja Schneider, Peggy Gou, Maya Jane Coles, and Eli &amp; Fur.
American DJ The Blessed Madonna has been called "one of the world's most exciting turntablists". Her stage name is a tribute to her mother's favorite Catholic saint, Black Madonna. In 2018, The Blessed Madonna played herself as an in-residence DJ for the video game "Grand Theft Auto Online", as part of the "After Hours" DLC.
There are various projects dedicated to the promotion and support of these practices such as Female DJs London. Some artists and collectives go beyond these practices to be more gender inclusive. For example, Discwoman, a New York-based collective and booking agency, describe themselves as "representing and showcasing cis women, trans women and genderqueer ["sic"] talent."
In Japan, the newest Bushiroad franchise: "D4DJ" focuses on an all-women DJ unit.
Equipment.
DJs use equipment that enables them to play multiple sources of recorded music and mix them to create seamless transitions and unique arrangements of songs. An important tool for DJs is the specialized DJ mixer, a small audio mixer with a crossfader and cue functions. The crossfader enables the DJ to blend or transition from one song to another. The cue knobs or switches allow the DJ to "listen" to a source of recorded music in headphones before playing it for the live club or broadcast audience. Previewing the music in headphones helps the DJ pick the next track they want to play, cue