A disc jockey (abbreviated D.J. or DJ) is a person who plays 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.

There are several types of disc jockeys. 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. Hip hop DJs select and play music using multiple turntables to back up one or more MCs/rappers, perform turntable scratching to create percussive sounds, and are also often 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.[1] 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.[2] According to a 2012 study, there are approximately 1¼ million professional disc jockeys in the world.[3]

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

House music is a genre of electronic dance music that originated in the American city of Chicago in the early 1980s. It was initially popularized circa 1984 in Chicago, but beginning in 1985, it fanned out to other major cities such as Baltimore, Detroit, Toronto, Mexico City, New York City, San Francisco, Boston, Montreal, Cancún, Manchester,[1] Miami, London,[1] and Paris. It then began to influence popular music in Europe, with songs such as "House Nation" by House Master Boyz and the Rude Boy of House (1987) and "Doctorin' the House" by Coldcut (1988) in the pop charts. Since the early to mid-1990s, house music has been infused in mainstream pop and dance music worldwide.

Early house music was generally dance-based music characterized by repetitive 4/4 beats, rhythms mainly provided by drum machines,[2] off-beat hi-hat cymbals, and synthesized basslines. While house displayed several characteristics similar to disco music, it was more electronic and minimalistic,[2] and the repetitive rhythm of house was more important than the song itself. House music today, while keeping several of these core elements, notably the prominent kick drum on every beat, varies a lot in style and influence, ranging from the soulful and atmospheric deep house to the more minimalistic microhouse. House music has also fused with several other genres creating fusion subgenres,[2] such as euro house, tech house, and electro house.

Many local Chicago house music artists suddenly found themselves with major label deals. House music proved to be a commercially successful genre and a more mainstream pop-based variation grew increasingly popular. Artists and groups such as Madonna,[2] Janet Jackson,[3] Björk, Kanye West,[4] and C+C Music Factory[2] incorporated the genre into their work. After enjoying significant success in the early to mid-90s, house music grew even larger during the second wave of progressive house (1999–2001). The genre has remained popular and fused into other popular subgenres, as the DJ Mag Top 100 DJs poll has been dominated by house DJs since the beginning of the polls. Today, house music remains popular in both clubs and in the mainstream pop scene while retaining a strong foothold on underground scenes across the globe.

Followers of Eli Druce