Anyone who has played in an orchestra or ensemble or sung in a chorus is probably aware of the cost of sheet music, even though much of it hearkens back to pre-20th century and has long since passed out of copyright. Thanks to the Internet and the idea of the wiki, however, such sheet music can be had for free from sites such as the International Music Score Library Project (IMSLP) and the Choral Public Domain Library (CPDL).
What is the difference to your pocketbook? Take a choir of 50 who intend to sing Pablo Casals' still-under-copyright piece O Vos Omnes. To buy enough copies of the choral arrangement could cost around $150.If, instead, the choir chose to sing Schubert's Magnificat D 483, the cost of sheet music would drop to the cost of photocopying, since it is free at CPDL.org.
The same applies to the 85,000 instrumental and orchestral works available from the IMSLP/Petrucci Music Library, a repository of public domain sheet music. Some of this music is old enough to have outlived copyrights, while a portion of it is from later and current composers who have released their music under a Creative Commons license.
The site offers music of the greatest composers, such as Bach, Beethoven and Mozart, as well as thousands of lesser-knowns. It also offers a generous sampling of folk songs from various countries.
The IMSLP is run as a wiki, meaning that volunteers post the music, others vet it. While the site takes great pains to avoid violating copyrights, the music is downloaded around the world. Those downloading music are expected to be aware of, and obey, any local copyrighting laws that may vary from those in Canada, where the site is hosted.
Free Sheet Music for Choirs and Orchestras Via the Internet