Originally, the "disc" in "disc jockey" referred to gramophone records, but now "DJ" is used as an all-encompassing term to describe someone who mixes recorded music from any sources, including cassettes, CDs, or digital audio files on a CDJ or laptop. DJs typically perform for a live audience in a nightclub or dance club or a TV, radio broadcast audience, or in the 2010s, 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.
DJs use equipment that can play at least two sources of recorded music simultaneously and mix them together. This allows the DJ to create seamless transitions between recordings and develop unique mixes of songs. Often, this involves aligning the beats of the music sources so their rhythms do not clash when they are played together, either so two records can be played at the same time, or to enable the DJ to make a smooth transition from one song to another. 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 pre-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 and cue up the track to the desired starting location so it will mix well with the currently playing music. 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.
The title "DJ" is also commonly used by DJs in front of their real names or adopted pseudonyms or stage names as a title to denote their profession (e.g., DJ Jazzy Jeff and DJ Q-bert). Some DJs focus on creating a good mix of songs for the club dancers or radio audience. Other DJs use turntablism techniques such as "scratching", in which the DJ or turntablist manipulates the record player turntable to create new rhythms and sounds. DJs need to have a mixture of artistic and technical skills for their profession, because they have to understand both the creative aspects of making new musical beats and tracks, and the technical aspects of using audio consoles, professional audio equipment, and, in the 2010s, Digital Audio Workstations and other computerized music gear. In many types of DJing, including club DJing and radio/TV DJing, a DJ also has to have charisma and develop a good rapport with the audience. Professional DJs often specialize in a specific genre of music, such as house music or hip hop music. DJs typically have an extensive knowledge about the music they specialize in. Many DJs are avid music collectors of vintage, rare or obscure tracks and records.
There are several types of disc jockey. Radio DJs or radio personalities introduce and play music that is broadcast on AM, FM, digital or Internet radio stations. Club DJs select and play music in bars, nightclubs or discothèques, or at parties, 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 (MC) at weddings or other events, 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 for DJs that specialize in different turntablism techniques, such as mixing, hip hop music-style "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 (or other sound sources) to back one or more MCs or rappers, but they also perform turntable "scratching" to create rhythmic and percussive sounds and create sound effects and beats. Hip hop DJs and are also often songwriters 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", chants or chats over pre-recorded rhythm tracks. The individual who helps the DJ by selecting tracks or records to be played is called the selector.
Many electronica artists and producers who also work as DJs often perform music by combining turntablism with keyboards, digital musical instruments, drum machines 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.
The songs, tracks and beats a DJ picks to play and the style in which the DJ mixes them defines a DJ's style. DJs are often connoisseurs of various music genres, and they often spend time in used record stores searching for rare or obscure tracks to use in their club sets. DJs also use DJ mixers to transition from song to song in different ways. One key technique used by DJs for seamlessly transitioning from one song to another is beatmatching. The DJ's style can and should be pliable, depending on what club he or she is playing in and what kind of music is expected of the DJ (e.g. a house music dance requires a different set list than a rave or a techno event). The DJ also has to "read" the mood of the dancers, and pick songs or styles of music that will keep the dancers on the dance floor.
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. Also, DJs who make a steady income from a venue, are also considered resident DJs. Wynn Nightlife and Hakkasan are well known for hiring high-profile DJs as residents with 'skyrocketing pay'.
As music technology has progressed, DJs have adopted different types of equipment to play and mix music, all of which are still commonly used. Traditionally, DJs used two turntables plugged into a DJ mixer to mix music on vinyl records. As compact discs became popular media for publishing music, specialized high quality CD players known as CDJs were developed for DJs. CDJs can take the place of turntables or be used together with turntables. Many CDJs can now play digital music files from USB flash drives or SD cards in addition to CDs. With the spread of portable laptop, tablet, and smartphone computers, DJs began using software together with specialized sound cards and DJ controller hardware. DJ software can be used in conjunction with a hardware DJ mixer or be used instead of a hardware mixer.
Turntables allow DJs to play vinyl records. By adjusting the playback speed of the turntable, either by adjusting the speed knob, or by manipulating the platter (e.g., by slowing down the platter by putting a finger gently along the side), DJs can match the tempos of different records so their rhythms can be played together at the same time without clashing or make a smooth, seamless transition from one song to another. This technique is known as beatmatching. DJs typically replace the rubber mat on turntables that keeps the record moving in sync with the turntable with a slipmat that facilitates manipulating the playback of the record by hand. With the slipmat, the DJ can stop or slow down the record while the turntable is still spinning. Direct-drive turntables are the type preferred by DJs, with the Technics SL-1200 being the most popular model of turntables for DJs. Belt-drive turntables are less expensive, but they are not suitable for turntablism and DJing, because the belt-drive motor does not like being slowed down, as it can stretch out the belt. Some DJs, most commonly those who play hip hop music, go beyond merely mixing records and use turntables as musical instruments for scratching, beat juggling, and other turntablism techniques.
CDJs are high quality digital media players made for DJing. They often have large jog wheels and pitch controls to allow DJs to manipulate the playback of digital files for beatmatching similar to how DJs manipulate vinyl records on turntables. CDJs often have features such as loops and waveform displays similar to DJ software. Originally designed to play music from compact discs, they now can play digital music files stored on USB flash drives and SD cards. Some CDJs can also connect to a computer running DJ software to act as a DJ controller.
DJ mixers are small audio mixing consoles specialized for DJing. Most DJ mixers have far fewer channels than a mixer used by a record producer or audio engineer; whereas standard live sound mixers in small venues have 12 to 24 channels, and standard recording studio mixers have even more (as many as 72 on large boards), basic DJ mixers may have only two channels. While DJ mixers have many of the same features found on larger mixers (faders, equalization knobs, gain knobs, effects units, etc), DJ mixers have a feature that is usually only found on DJ mixers: the crossfader. The crossfader is a type of fader that is mounted horizontally. DJs used the crossfader to mix two or more sound sources. The midpoint of the crossfader's travel is a 50/50 mix of the two channels (on a two channel mixer). The far left side of the crossfader provides only the channel A sound source. The far right side provides only the channel B sound source (e.g., record player number 2). Positions in between the two extremes provide different mixes of the two channels. Some DJs use a computer with DJ software and a DJ controller instead of an analog DJ mixer to mix music, although DJ software can be used in conjunction with a hardware DJ mixer.
DJs generally use higher quality headphones than those designed for music consumers. DJ headphones have other properties useful for DJs, such as designs that acoustically isolate the sounds of the headphones from the outside environment (hard shell headphones), flexible headbands and pivot joints to allow DJs to listen to one side of the headphones, while turning the other headphone away (so he/she can monitor the mix in the club), and replaceable cables. Replaceable cables enables DJs to buy new cables if a cable becomes frayed, worn, or damaged, or if a cable is accidentally cut.
Closed-back headphones are highly recommended for DJs to block outside noise as the environment of DJ usually tend to be very noisy. Standard headphones have 3.5mm jack but DJ equipment usually requires ¼ inch jack. Most of specialized DJ Headphones have an adapter to switch between 3.5mm jack and ¼ inch jack. Detachable coiled cables are perfect for DJ Headphones.
DJs have changed their equipment as new technologies are introduced. The earliest DJs in pop music, in 1970s discos, used record turntables, vinyl records and audio consoles. In the 1970s, DJs would have to lug heavy direct drive turntables and crates of records to clubs and shows. In the 1980s, many DJs transitioned to compact cassettes. In the 1990s and 2000s, many DJs switched to using digital audio such as CDs and MP3 files. As technological advances made it practical to store large collections of digital music files on a laptop computer, DJ software was developed so DJs could use a laptop as a source of music instead of transporting CDs or vinyl records to gigs. Unlike most music player software designed for regular consumers, DJ software can play at least two audio files simultaneously, display the waveforms of the files on screen and enable the DJ to listen to either source.
The waveforms allow the DJ see what is coming next in the music and how the playback of different files is aligned. The software analyzes music files to identify their tempo and where the beats are. The analyzed information can be used by the DJ to help manually beatmatch like with vinyl records or the software can automatically synchronize the beats. Digital signal processing algorithms in software allow DJs to adjust the tempo of recordings independently of their pitch (and musical key, a feature known as "keylock". Some software analyzes the loudness of the music for automatic normalization with ReplayGain and detects the musical key. Additionally, DJ software can store cue points, set loops, and apply effects.
As tablet computers and smartphones became widespread, DJ software was written to run on these devices in addition to laptops. DJ software requires specialized hardware in addition to a computer to fully take advantage of its features. The consumer grade, regular sound card integrated into most computer motherboards can only output two channels (one stereo pair). However, DJs need to be able to output at least four channels (two stereo pairs, thus Left and Right for input 1 and Left and Right for input 2), either unmixed signals to send to a DJ mixer or a main output plus a headphone output. Additionally, DJ sound cards output higher quality signals than the sound cards built into consumer-grade computer motherboards.
Special vinyl records (or CDs/digital files played with CDJs) can be used with DJ software to play digital music files with DJ software as if they were pressed onto vinyl, allowing turntablism techniques to be used with digital files. These vinyl records do not have music recordings pressed on to them. Instead, they are pressed with a special signal, referred to as "timecode", to control DJ software. The DJ software interprets changes in the playback speed, direction, and position of the timecode signal and manipulates the digital files it is playing in the same way that the turntable manipulates the timecode record.
This requires a specialized DJ sound card with at least 4 channels (2 stereo pairs) of inputs and outputs. With this setup, the DJ software typically outputs unmixed signals from the music files to an external hardware DJ mixer. Some DJ mixers have integrated USB sound cards that allow DJ software to connect directly to the mixer without requiring a separate sound card.
DJ software can be used to mix audio files on the computer instead of a separate hardware mixer. When mixing on a computer, DJs often use a DJ controller device that mimics the layout of two turntables plus a DJ mixer to control the software rather than the computer keyboard & touchpad on a laptop, or the touchscreen on a tablet computer or smartphone. Many DJ controllers have an integrated sound card with 4 output channels (2 stereo pairs) that allows the DJ to use headphones to preview music before playing it on the main output.
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 advanced music-mixing procedures than club DJs, who rely on a smooth transition between songs using a range of techniques. However, some radio DJs are experienced club DJs, so they use the same sophisticated mixing techniques.
Club DJ turntable techniques include beatmatching, phrasing and slip-cueing to preserve energy on a dance floor. 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.
In DJ culture, miming refers to the practice of DJ's pantomiming the actions of live-mixing a set on stage while a pre-recorded mix plays over the sound system. Miming mixing in a live performance is considered to be controversial within DJ culture. Some within the DJ community say that miming is increasingly used as a technique by celebrity model DJs who may lack mixing skills, but can draw big crowds to a venue.
During a DJ tour for the release of the French group Justice's A Cross the Universe in November 2008, controversy arose when a photograph of Augé DJing with an unplugged Akai MPD24 surfaced. The photograph sparked accusations that Justice's live sets were faked. Augé has since said that the equipment was unplugged very briefly before being reattached and the band put a three-photo set of the incident on their MySpace page. After a 2013 Disclosure concert, the duo was criticized for pretending to live mix to a playback of a pre-recorded track. Disclosure's Guy Lawrence said they did not deliberately intend to mislead their audience, and cited miming by other DJs such as David Guetta.
The term "disc jockey" was ostensibly coined by radio gossip commentator Walter Winchell in 1935, and the phrase first appeared in print in a 1941 Variety magazine, used to describe radio personalities who introduced phonograph records on the air. Playing recorded music for dancing and parties rose with the mass marketing of home phonographs in the late 19th century, and Jimmy Savile is credited with hosting the first live DJ dance party in 1943. Savile is also credited as the first to present music in continuous play by using multiple turntables. In 1947, the Whiskey A Go-Go opened in Paris as the first discoteque. In the 1960s, Rudy Bozak began making the first DJ mixers, mixing consoles specialized for DJing.
In the 1960s, Jamaican sound system culture emerged, with Jamaican deejays such as King Tubby and Lee "Scratch" Perry pioneering dub music in the late 1960s. They experimented with tape-based composition, emphasized repetitive rhythmic structures (often stripped of their harmonic elements), electronically manipulated spatiality, sonically manipulated pre-recorded musical materials from mass media, deejays toasted (boastful chanting) over pre-recorded music, and they remixed music. Jamaican deejays later had a significant impact on hip hop DJs in the 1970s.
DJ turntablism has origins in the invention of direct-drive turntables. Early belt-drive turntables were unsuitable for turntablism and mixing, since they had a slow start-up time, and they were prone to wear-and-tear and breakage, as the belt would break from backspinning or scratching. The first direct-drive turntable was invented by Shuichi Obata, an engineer at Matsushita (now Panasonic), based in Osaka, Japan. It eliminated belts, and instead employed a motor to directly drive a platter on which a vinyl record rests. In 1969, Matsushita released it as the SP-10, the first direct-drive turntable on the market, and the first in their influential Technics series of turntables.
In 1972, Technics started making their SL-1200 turntable, which became the most popular turntable for DJs due to its high torque direct drive design. The SL-1200 had a rapid start and its durable direct drive enabled DJs to manipulate the platter, as with scratching techniques. Hip hop DJs began using the Technics SL-1200s as musical instruments to manipulate records with turntablism techniques such as scratching and beat juggling rather than merely mixing records. These techniques were developed in the 1970s by DJ Kool Herc, Grand Wizard Theodore, and Afrika Bambaataa, as they experimented with Technics direct-drive decks, finding that the motor would continue to spin at the correct RPM even if the DJ wiggled the record back and forth on the platter. Although Technics stopped producing the SL-1200 in 2010, they remain the most popular DJ turntable due to their high build quality and durability.
In 1980, Japanese company Roland released the TR-808, an analog rhythm/drum machine, which has unique artificial sounds, such as its booming bass and sharp snare, and a metronome-like rhythm. Yellow Magic Orchestra's use of the instrument in 1980 influenced hip hop pioneer Afrika Bambaataa, after which the TR-808 would be widely adopted by hip hop DJs, with 808 sounds remaining central to hip hop music ever since. The Roland TB-303, a bass synthesizer released in 1981, had a similar impact on electronic dance music genres such as techno and house music, along with Roland's TR-808 and TR-909 drum machines.
In 1982, the Compact Disc (CD) format was released, popularizing digital audio. 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 (a.k.a. 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 2001, Pioneer DJ began producing the CDJ-1000 CD player, making the use of digital music recordings with traditional DJ techniques practical for the first time. As the 2000s progressed, laptop computers became more powerful and affordable. DJ software, specialized DJ sound cards, and DJ controllers were developed for DJs to use laptops as a source of music rather than turntables or CDJs. In the 2010s, like laptops before them, tablet computers and smartphones became more powerful & affordable. DJ software was written to run on these more portable devices instead of laptops, although laptops remain the more common type of computer for DJing.
In Western popular music, women musicians have achieved great success in singing and songwriting roles, with top examples being Madonna, Celine Dion and Rihanna. However, there are relatively few women DJs or turntablists. Part of this may stem from a general low percentage of women in audio technology-related jobs. A 2013 Sound on Sound article 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 female producers achieving great things in music, they are less well-known than their male 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 male 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 states "the male-centricity of 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 explains: "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 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 DJ-ing, sound engineering and producing" are "not necessarily about her 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".
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 talent."
Tom Cosm at the decks at the Rainbow Serpent Festival in 2008
Jeff Mills, live with three Pioneer CDJs and a Roland TR-909 drum machine, 2007
Trance DJ Ferry Corsten in Canada
DJ Dougal and Gammer