What's abc? abc is a system of notation for music which uses ordinary ASCII text to represent the symbols which you would normally write on music manuscript. It is simple, human-readable, and if you can touch type it is much faster to enter abc at the keyboard than it is to use a graphical music program to place notes on a staff using the mouse. Because it's plain old ASCII, you can use it to post music to newsgroups (it's very bad netiquette to post MIDI, GIF or other binary files to text-only newsgroups) email tunes to your friends, or use it as a highly efficient way of storing music (you can store thousands of tunes on a single floppy disk).
abc was invented by Chris Walshaw, and for a complete description of the language, links to other software and music collections in abc go to his abc home page.