MML is a music description language used in sequencing music on a number of computer and video game system platforms. It's basically a text file which can be compiled into a native music file for a video game console.

Several dialects of MML exist:

NES / Famicom 2A03
- MCK (internal only)
- PPMCK (All expansions)
- NSD.Lib (All expansions, ad-hoc OPLL support)
- OFGS (Some expansions + PCM synth channels)

SPC-700
- AddMusicK

PC-x801 YM2608 and YM2203
- Professional Music Driver (PMD)
- FMP
- MDRV2

Multiple systems
- XPMCK (GB / YM2151 / YM2612 / SN76489 / AY / Pokey / PC-Engine)
- VGMCK (most VGM formats with unofficial extension for NES expansion chips)