What Does Music Sequencer Mean?
A music sequencer is a software application or a digital electronic device that can record, save, play and edit audio files. The audio information can be stored in various data formats such as MIDI (Musical Instrument Digital Interface), CV/G (Control Voltage/Gate) or OSC (Open Sound Control). A music sequencer can be introduced as a plugin with musical instruments or as a standalone unit.
A music sequencer is also known simply as a sequencer.
Techopedia Explains Music Sequencer
A software-based musical sequencer is a program that composes several sequences of digital audio together from a number of operations. In the case of a MIDI sequencer, audio is stored in the form of a series of events, meaning that it does not record the actual audio but the sequence of actions taken on each time instance — which note was pressed at what time and for how long.
Hardware-based musical sequencers are generally lightweight and portable. Modern sequencers are frequently in the form of a keyboard, and can help in controlling and composing music out of virtual instruments. They can help musicians by replacing individual synthesizers.