Public Domain refers to scores that are now out of copyright and thus may be freely distributed. In the US, this generally means scores published before 1923. In many other countries, copyright expires 50 or 70 years after the death of the author. To know which scores you may legally use, please look up the relevant copyright laws of your country.
Please submit only sites offering free downloads of Public Domain sheet music. Both scans of original editions as well as newly typeset scores based on public domain editions are admissible.