What is MusicXML?

MusicXML is the standard code for exchanging scores between various score editors and for some of the most innovative music hardware systems.  It was developed by Michael Good in 2000, although the most recent version (3.0) was published in August 2011.  It is in addition an open format for use in Free Software, currently used in over 160 music applications (list of applications which import and edit in MusicXML (www.musicxml.com/software). MusicXML was designed to be the published digital music equivalent of MP3.

Example of the note C in 4/4 time, as explained on the official MusicXML website