MIDI is an acronym for Musical Instrument Digital Interface. It is basically a sequence programming protocol, commonly used for composing music. The concept for MIDI was invented in the 80's when there was no common
communication standard between synthesizers. Over the years, it has gotten a reputation for sounding like crap. What people keep forgetting, is that MIDI isn't
responsible for producing sound. The synthesizer is. Most music teaching programs, like Synthesia, use MIDI files.
The most common MIDI files utilize General MIDI 1.0, although there exists MIDI 2.0, with HD-MIDI being in development right now.
Unfortunately, GM 2.0 isn't supported by a lot of synthesizers.