MIDI, or Musical Instrument Digital Interface, is a protocol that allows electronic musical instruments, computers, and other devices to communicate with each other. MIDI data can be used to control a wide variety of musical parameters, including note pitch and duration, instrument sounds, and effects. MIDI is also used to create and edit music notation and to control live performances.
Arranging a song in MIDI involves creating a MIDI sequence that contains the musical data for the song. This sequence can be played back on a MIDI synthesizer or other device to produce the song. Arranging a song in MIDI can be a complex process, but it can also be a very rewarding one. It allows you to experiment with different musical ideas and to create sophisticated and nuanced arrangements.