Public domain

The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired, been forfeited, expressly waived, or may be inapplicable. Because no one holds the exclusive rights, anyone can legally use or reference those works without permission. As examples, the works of William Shakespeare, Ludwig van Beethoven, Leonardo da Vinci and Georges Méliès 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 a country's copyright laws, and are therefore in the public domain; for example, in the United States, items excluded from copyright include the formulae of Newtonian physics and cooking recipes. Other works are actively dedicated by their authors to the public domain (see waiver); examples include reference implementations of cryptographic algorithms, and the image-processing software (created by the National Institutes of Health). 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". As rights vary by country and jurisdiction, a work may be subject to rights in one country and be in the public domain in another. Some rights depend on registrations on a country-by-country basis, and the absence of registration in a particular country, if required, gives rise to public-domain status for a work in that country. The term public domain may also be interchangeably used with other imprecise or undefined terms such as the public sphere or commons, including concepts such as the "commons of the mind", the "intellectual commons", and the "information commons". Although the term domain did not come into use until the mid-18th century, the concept can be traced back to the ancient Roman law, "as a preset system included in the property right system".