In 1971 Michael Hart started the Project Gutenberg. The PG is a volunteer effort to digitize, archive, and distribute cultural works. It is the oldest digital library. Most of its items are the full texts of public domain books. The project tries to make the items in its collection as free as possible, in long-lasting, open formats that can be used on almost any computer.
The PG is legal because the copyright on this books has expired. We often don’t think about it because we are used to buy books, but the original text of all the works whose author is died from more than a crtain amount of years (the time could differs in different countries) can be freely and legally copied. I said “original text” because the translations are generally copyrighted.
There are 18,000 free books in the Project Gutenberg Online Book Catalog.
Mutopia Project is similar in spirit to Project Gutenberg, but consists of free sheet music.
Broadly speaking, copyright on a creative work expires 70 years after the creator’s death. This means that the works of Bach, Mozart, Beethoven and many other composers are in the public domain – in principle, they may be copied and performed without restriction.
However, you may not normally copy or perform a sheet music edition which you can buy, because an editor also has a copyright on the edition, and an arranger may have, too. The copyright on the edition only expires when all these people have been dead for 70 years. Additional restrictions in the USA mean that only works published there prior to 1923 are in the public domain. Only sufficiently old editions fulfil these criteria, and are therefore in the public domain.
But for a lot of classical music, editions do exist which are old enough, especially in libraries and private collections. The quality of the editorial work is generally as high as in recent editions, if not higher. Several composers were also notable as editors. (For example, Brahms’s editions of Mozart works are now in the public domain)
The idea behind the Mutopia Project is that volunteers typeset these editions on a computer, using the GNU Lilypond typesetting software, and make them freely available.
The Mutopia Project also contains a growing number of modern editions, arrangements and new music. The respective editors, arrangers and composers have chosen to make these works freely available. All may be freely downloaded, printed, copied, distributed, modified, performed or recorded.
All music is available as Postscript (.ps) and PDF (.pdf) files, for both A4 and Letter paper sizes, as well as Lilypond’s own file format (.ly).