One of the problems once faced by wanna-be MIDI musicians was that humans read musical notes differently than MIDI sound modules. To oversimplify, we use letters to represent each note (C sharp in the fourth octave, for example), and MIDI sound modules use numbers. Since most MIDI sound modules can play up to 128 notes, a MIDI sound module will number them from 0 to 127. The problems arose when different manufacturers started using different numbers to correspond with different notes. A C sharp in the sixth octave might correspond to number 61 on sound modules made by one manufacturer, and to a 49 on one made by another. Were talking serious chaos here imagine what it would do to your composition if you made it on a Roland and tried to play it on another manufacturers sound module. Even worse, some very disorganized manufacturers assigned different numbers to different notes even in the same sound module depending on which instrument you played. In other words, you just about needed a degree in computer science to figure it all out, and composing a song meant about 3 times as much grunt work as actual composing.
The General MIDI standard organized this musical chaos by...