Are there any free sheet music composers available for download?
For simple tunes / songs, I use ABC notation (write scores just with letters, numbers and some characters - quick and flexible!) with the tool EasyABC - a great package that lets you write / import music in ABC notation and instantly converts it into pretty looking sheet music. More about ABC notation here - it's amazingly simple and powerful.For complex scores and for composition, I use Musescore: A great open source scorewriter, really stable and capable, output quality is very good, playback really fine, too. For most scoring solutions it works perfectly well, albeit not always intuitive (text input could still be improved, for instance), and some special cases are not yet implemented (non-standard accidentals for quartertones, for instance). But generally very recommendable, also because it supports a lot of input and output formats and has a friendly and big user community.