A sequencer is considered as a device that record and play back a sequence of control information for an electronic musical instrument. Application of software is also possible for a music sequencer. Programs can be written for recording and playing back the notes played by a musician.
With advancement in technology, sequencers with more features are obtained. It enables the recording of multitrack audio, and control of virtual instruments known as plug-ins. As a result there has been a replacement of synthesizers with software equivalents that ran inside a sequencer software. Earlier, control voltage/trigger interface is used by analog music sequencers. They are now replaced by using digital sequencers like MIDI. Software music sequencers run on personal computers.
There is an interchangeable use of the term music sequencer and digital audio workstation. The term sequencer is used for software today. However, their own proprietary built-in MIDI sequencers are included in workstation keyboards. Drum machines and groove boxes use step sequencers. Some of the examples of music sequencing software are Digital Performer, energyXT, Ableton Live, and Emagic Logic.