MuseScore is a free and open-source scorewriter for Windows, OS X, and Linux. Created by Werner Schweer, it is released as free and open source software under the GNU General Public License
MuseScore’s main purpose is the creation, editing and printing of various types of musical scores in a “What-You-See-Is-What-You-Get” environment. It supports most types of notation, including jazz lead sheets, and prints or exports high quality engraved sheets. MuseScore’s notation engine conforms to industry notation standards.
MuseScore can natively import MusicXML, MIDI, Band-in-a-Box, capella (in the cap3 format, not CapXML) and Overture formats, as well as its own MuseScore format. It can export to MusicXML, MIDI, and LilyPond file formats. Audio can be exported to WAV and Ogg files, and engraved output can be exported to PDF, SVG, PNG, and PostScript formats, or it can be printed directly.
MuseScore.com allows playback of a score in any browser supporting the HTML5 MP3 tag. A score can also be linked to an on-line video, so that one may follow the sheet music while watching a video featuring that score.