The portion of an electronica track at its end, where a basic pattern repeats unaltered for a period of typically 10-20 seconds, until the track ends. The purpose of the runout is to facilitate the DJ transitioning to the next song without a break in between; the DJ beat matches the next track and then segues it in, and during the segue the runout and the intro of the next track are both heard. A skillful DJ can do this so that it sounds like only one track is playing, such that the casual listener may not even realize that another track has begun. Often the runout consists solely of a four-count drum machine pattern repeating, with no melodic or harmonic elements; this facilitates transitioning to another track which is in a different musical key.
(The term "runout" stems from the time in the past when vinyl phonograph records were the dominant form of recorded music. The runout was an area at the innermost part of the disc, next to the label edge, where the groove spiraled rapidly across a gap of 1 cm or so (sometimes wider), to an innermost circular groove where the stylus remained until it was removed from the disc. The purpose of the runout was to take up unneeded space on the disc, provide a place to put in numbers that identified the master disc that the record was pressed from, and trigger "record changer" turntables and jukeboxes to cue up the next disc to be played. It was not intended that music or sound be recorded in the runout area, but artists sometimes did so as a joke; when this was done, the portion recorded in the innermost circular groove would repeat indefinitely until the stylus was lifted. The monotony of the unchanging pattern gave the word "runout" its current meaning in electronica.)