A DJ mixer is a type of audio mixing console used by disc jockeys (DJs). DJs playing music for dancers at a club use the mixer to make smooth transitions between different songs which are played on sound sources that are plugged into the mixer. These sound sources could be turntables, CD players, or iPods. A "scratching" DJ uses the mixer in combination with turntables or specialized DJ CD players to create unique sound effects.
The DJ mixer also allows the DJ to use headphones to cue the next song before playing it. The key features that differentiate a DJ mixer from other types of audio mixers are the ability to redirect (cue) a non-playing source to headphones, in order to find the desired part of a song and the presence of a crossfader, which allows for an easier transition between two sources.