|This page documents an English Wikipedia content guideline.|
For all practical purposes on Wikipedia, the public domain comprises copyright-free works: anyone can use them in any way and for any purpose. Proper attribution to the author or source of a work, even if it is in the public domain, is still required in order to comply with relevant policies.
- that were not eligible for copyright in the first place, or
- whose copyright has expired, or
- that were released into the public domain by the copyright holder.
However, there is no such thing as the public domain on the Internet. International treaties, like the Berne Convention, are not self-executing and do not supersede local law. There is no globally valid "International Copyright Law" that would take precedence over local laws. Instead, signatory countries of the Berne Convention have adapted their laws to comply with the minimum standards set forth by the treaty, often with stronger provisions than required. Whether or not something is copyright-free in some country depends on the individual country.
The Wikimedia Foundation, the legal body responsible for Wikipedia, is based in the US state of California. Although legislation is sometimes unclear about which laws are to apply on the Internet, the primary law relevant for Wikipedia is that of the United States. For re-users of Wikipedia content, it is the laws of their respective countries.
In the US, any work published before January 1, 1928, anywhere in the world is in the public domain. Other countries are not bound by that 1928 date, though. Complications arise when special cases are considered, such as trying to determine whether a work published later might be in the public domain in the US, or when dealing with unpublished works. When a work has not been published in the US, but in some other country, that other country's copyright laws also must be taken into account. Re-users of Wikipedia content also might find the explanations here useful.