Beatmatching

Beatmatching is a disc jockey technique of pitch shifting or timestretching a track to match its tempo to that of the currently playing track. This allows beatmixing, smooth mixing between the tracks without stopping the beat or changing the tempo.

The technique was developed to keep the people from leaving the dancefloor at the end of the song. These days it is considered very basic among DJs in electronic dance music genres, and it is standard practice in clubs to keep the constant beat through the night, even if DJs change in the middle.