D.J.

A disc jockey (abbreviated DJ, D.J. or deejay) is a person who mixes recorded music as it is playing. 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 or broadcast audience, but DJs also create mixes that are recorded for later sale and distribution.

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. DJ equipment also allows the DJ to preview a source of recorded music in headphones before playing it for the 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.

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.

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 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 (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.

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