Similar to what we think of as a musical part. A MIDI Part can be a drum part, bass part, keyboard part, etc. In MIDI we think of all the data on a particular MIDI channel as a “part.” In a multitimbral instrument several different MIDI Parts can be played simultaneously. The structure of MIDI gives us a way to subdivide musical parts into multiple MIDI parts if we want. We can have the bass drum and snare drum be two different parts played by different instruments . Or we can have a dense keyboard layer that is actually played by multiple sound modules. Each of these may be its own MIDI Part, meaning it is separate data on a separate MIDI channel.