The public domain (PD) consists of all the creative work to which no exclusive intellectual property rights apply. Those rights may have expired,[1] been forfeited,[2] expressly waived, or may be inapplicable.[3] 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, Miguel de Cervantes, Zoroaster, Lao Zi, Confucius, Aristotle, L. Frank Baum, 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.[1] 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.[4] Other works are actively dedicated by their authors to the public domain (see waiver); examples include reference implementations of cryptographic algorithms,[5][6][7] and the image-processing software ImageJ (created by the National Institutes of Health).[8] 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".[9]
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".[10] The Romans had a large proprietary rights system where they defined "many things that cannot be privately owned"[10] as res nullius, res communes, res publicae and res universitatis.[11] The term res nullius was defined as things not yet appropriated.[12] The term res communes was defined as "things that could be commonly enjoyed by mankind, such as air, sunlight and ocean."[10] The term res publicae referred to things that were shared by all citizens, and the term res universitatis meant things that were owned by the municipalities of Rome.[10] When looking at it from a historical perspective, one could say the construction of the idea of "public domain" sprouted from the concepts of res communes, res publicae, and res universitatis in early Roman law.[10]
When the first early copyright law was originally established in Britain with the Statute of Anne in 1710, public domain did not appear. However, similar concepts were developed by British and French jurists in the 18th century. Instead of "public domain", they used terms such as publici juris or propriété publique to describe works that were not covered by copyright law.[13]