Works in the public domain are those whose exclusive intellectual property rights have expired, have been forfeited, or are inapplicable. For example, the works of Shakespeare and Beethoven, and most of the early silent films, are all now in the public domain by either being created before copyrights existed or leaving the copyright term. Examples for works not covered by copyright which are therefore in the public domain, are the formulae of Newtonian physics, cooking recipes and all software before 1974. Examples for works actively dedicated into public domain by their authors are reference implementations of cryptographic algorithms, NIH's ImageJ, and the CIA's The World Factbook. The term is not normally applied to situations where the creator of a work retains residual rights, in which case use of the work is referred to as "under license" or "with permission".
As rights are country-based and vary, a work may be subject to rights in one country and be in the public domain in another.

License information: CC BY-SA 3.0
MPAA: G
Go to source: https://en.wikipedia.org/wiki/Public_domain