audio/midi

Not audio at all, strictly speaking — a Standard MIDI File is sheet music for synthesizers, note events with timestamps, which is why a three-minute song fits in a few kilobytes. The type is a de facto convention (mime-db carries it from Apache's list) rather than an IANA registration, and how a file sounds depends entirely on the instrument set of whatever renders it. Every SMF opens with the MThd header chunk, one of the most reliable signatures in this registry.

.mid and .midi are interchangeable; .kar is the karaoke variant with embedded lyrics.

Defined by Standard MIDI Files 1.0 (MIDI Association). Registry facts from the IANA media-types registry via mime-db.