A device that records and plays back a sequence of control information for an electronic musical instrument. Though the term 'sequencer' is today used primarily for software, some hardware synthesizers (synthesizer) and almost all music workstations include a built-in MIDI sequencer. There are also standalone hardware MIDI sequencers. Music can also be sequenced using trackers such as ModPlug Tracker, and some of those are able to sequence MIDIevents too.