MIDI controller
An instrument with no sound of its own: keys, pads and knobs that just send MIDI to something that can make noise.
Before computers it was called a master keyboard and drove racks full of sound modules. Today the sound lives in a DAW or plugin, and the controller sends notes with velocity plus CC messages for knobs and sliders. Most connect over USB MIDI and are class-compliant, so no driver is needed.
The form factor has sprawled: pad grids such as the Novation Launchpad (2009) and Ableton Push were built to launch clips, not to play melodies. Mapping a knob to a parameter is usually done with MIDI learn. The expensive part of a controller is rarely the electronics but the keybed — weighted hammer-action keys cost more than everything else in the box.