MML is a format of writing music. Some programs using MML includes ppMCK for the Nintendo Family Computer and XPMCK for many other systems; QBASIC has a form of MML in the PLAY command.
For example this is the major C scale of eighth notes and then the quarter note for the high note.
l8cdefgab>c4<
Although QBASIC cannot make polyphonic music and cannot change volumes or waveforms or anything like that, other programs such as ppMCK can make polyphonic music in multiple tracks, with volume envelopes, loops, and various other features.
MML is mostly common in Japan, although it is used elsewhere, too.
It's common for cheesy video games, but is difficult to extend to provide more (potential) control over individual notes.
I happen to disagree; you are given as much control as other software (although it depends what MML compiler is being used). Often they can be done by macros instead of entering them every time, too.
See original on c2.com 