What is MIDI?
MIDI stands for Musical Instrument Digital Interface. It is a protocol that lets instruments, computers, and music software exchange performance data. MIDI contains no sound: it records instructions such as which note to play, when to play it, and how strongly it was triggered.
When you press a key on a MIDI keyboard, it does not send audio. It sends a message: "Note C4 was pressed at velocity 95." Your DAW receives that message and tells a virtual instrument to produce the sound. Change the instrument and the same MIDI notes can produce a completely different result.
What MIDI Messages Carry
MIDI messages are small, structured instructions. Each message communicates a particular event or parameter change to the receiving instrument or software.
Note On / Note Off
Start playing a note, stop playing a note. A Note On is normally followed by a Note Off; some MIDI devices also use a Note On with velocity 0 to stop the note.
Velocity
A value from 0 to 127 that represents how strongly the note was triggered. A receiving instrument may map velocity to volume, tone, or another parameter, so its exact effect depends on the patch.
Channel
MIDI has 16 channels, numbered 1-16. A device can use channels to route notes and controller data to different sounds or parts.
Control Change (CC)
Knobs and sliders - things like modulation wheel, sustain pedal, and expression. These adjust parameters in real time while notes are playing.
Why MIDI Matters
MIDI was introduced in the early 1980s so instruments from different manufacturers could communicate. It remains useful because the data is compact, editable, and separate from the sound source.
Tiny file size. A full MIDI arrangement is just a few kilobytes. An equivalent audio recording would be megabytes. MIDI files are the grocery list, not the groceries.
Total flexibility. You can change every note, adjust timing, swap instruments, shift key, or alter tempo - all without losing quality. Try doing that with a recording.
Broad compatibility. Standard MIDI files can be imported by most DAWs and many hardware and software instruments. Details such as mappings, controller support, and plug-in presets can still vary between systems.
How This Connects
When you use Starts or Progressions on produc.ing, every chord, melody, and bass line you generate is MIDI data. The piano roll you see is a visual representation of MIDI notes. When you export, you get a MIDI file that any DAW can open - ready to assign your own instruments and shape into a finished track.
Key takeaway
Try it
For each message, identify what it controls: “play C4”, “release C4”, “play it harder”, or “move the sustain pedal”. Label them Note On, Note Off, velocity, or Control Change, then explain why none of them contains the instrument's sound.
Extension: describe one way the same MIDI notes could sound different after you swap the virtual instrument.
MIDI is instructions, not sound. It tells instruments what to play, when, and how hard. Because it's data rather than audio, you can edit, rearrange, and reassign sounds with complete freedom.
Next: how MIDI represents specific pitches and dynamics with note numbers and velocity.
See MIDI in action
Starts generates MIDI arrangements you can export to any DAW.