For questions related to the open-source music notation software or its accompanying sheet-music sharing website. Questions may also necessitate the notation and/or engraving tags.
MuseScore (home page) is a scorewriter, or musical notation software. It is open-source and available for free for Windows, Linux, and Mac.
It can read and write several file formats, and supports midi playback and note entry.
MuseScore.com is a website for sharing sheet music which integrates with the MuseScore program.