Public domain
As examples, the works of William Shakespeare and Ludwig van Beethoven, and most early silent films, are in the public domain either by virtue of their having been created before copyright existed, or by their copyright term having expired. Some works are not covered by copyright, and are therefore in the public domain—among them the formulae of Newtonian physics, cooking recipes, and all computer software created prior to 1974. Other works are actively dedicated by their authors to the public domain (see waiver); some examples include reference implementations of cryptographic algorithms, the image-processing software ImageJ (created by the National Institutes of Health), and the CIA's World Factbook. The term public domain 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".
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