Record jockey, usually abbreviated as DJ, is the person who plays recorded music for the live audience. The most common types of DJs include broadcast DJs, club DJs performing at nightclubs or music festivals, and disc singers who use a jukebox (usually a turntable) to manipulate the sound on a gramophone record. Originally, the term "record" in "record jockey" refers to a gramophone record, but in the 2010's, DJ was used as an all inclusive term to describe someone mixing recorded music (including cassettes, CDs or digital audio files) from any source. CDJ or laptop. DJs usually use the title "DJ" before their real name, pseudonym or stage name. In the 2010's, although there were guest singers to sing the whole song, DJ became a famous singer in his repertoire, such as Marc Ronson's 2015 hit uptown funk.

DJs use audio devices that can play at least two recorded music sources at the same time and mix them together to create a seamless transition between recordings and develop unique song mixes. Generally, this involves aligning the beats of the music sources so that their rhythms and rhythms don't conflict when playing together, and achieving a smooth transition from one song to another. DJs usually use special DJ mixers, small audio mixers with cross push and prompt functions to mix or transition one song to another. The mixer is also used to pre listen to the source of the music recorded in the headset and adjust the track to be played to mix with the currently playing music. DJ software can be used with DJ controller devices to mix audio files on a computer rather than a console mixer. DJs can also use microphones to speak to the audience; effect units (such as reverb for sound effects) and electronic instruments (such as drum machines and synthesizers).

At first, "record" in "record jockey" refers to gramophone record, but now "DJ" is used as an all inclusive term to describe the audio files of people who record mixed music from any source (including vinyl record, tape, CD or digital music) stored on USB memory stick or laptop. DJs usually perform for live audiences in nightclubs or dance clubs or on television, radio stations, or online stations in the 2010's. DJ also creates mixes, remixes and tracks, and records them for later sale and distribution. In hip-hop music, DJs may use percussion, bass and other music content sampled from existing recordings to make beats. In hip-hop, rappers and MC use these beats to rap.

DJs use devices that can play at least two recorded music sources at the same time and mix them together. This allows DJs to create seamless transitions between recordings and develop unique song mixes. Usually, this involves aligning the beats of the music source so that they don't clash when playing together, so you can play two records at the same time, or make DJs transition smoothly from one song to another. An important tool of DJ is the special DJ mixer, which is a small audio mixer with the function of cross push and prompt. Cross push allows DJs to mix or transition from one song to another. The prompt knob or switch allows the DJ to "listen" to the recorded music source in the headset before playing music for the live club or broadcast audience. Previewing music in the headset can help DJs choose the next track they want to play, prompt the track to the desired starting position, and align the beats of the two tracks without the traditional use of automatic synchronization technology. This process ensures that the selected song will mix well with the currently playing music. DJs can also use microphones to speak to the audience; effect units such as reverb to create sound effects; and electronic instruments such as drum machines and synthesizers.

The title "DJ" is also commonly used by DJs when their real name or pseudonym or stage name is used as the title of their profession (for example, DJ Jazz Jeff, DJ qbert, DJ shadow and DJ Yoda). Some DJs focus on creating great songs for club dancers or radio listeners. Other DJs use turntable techniques such as scraping, where the DJ or turntable list operates the turntable of the jukebox to create new rhythms and sounds. DJs need to integrate artistic and technical skills in their careers, because they need to understand not only the creative aspects of making new music beats and tracks, but also the use of mixing consoles, professional audio equipment and the technical aspects of the 2010's, digital audio workstations and other computer music equipment. In many types of DJs, including club DJs and radio / TV DJs, DJs must also be charismatic and have a good rapport with the audience. Professional DJs usually specialize in certain types of music, such as home music or hip-hop music. DJs usually have a broad understanding of the music they are good at. Many DJs are avid music collectors who have collected old-fashioned, rare or obscure tracks and records.