- 1: land owned directly by the government
- 2: the realm embracing property rights that belong to the community at large, are unprotected by copyright or patent, and are subject to appropriation by anyone
Works in the public domain are those whose intellectual property rights have expired, have been forfeited, or are inapplicable. Examples include the works of Shakespeare and Beethoven, The King James Bible, most of the early silent films, the formulae of Newtonian physics, and the patents on powered flight. 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".
In informal usage, the public domain consists of works that are publicly available; while according to the formal definition, it consists of works that are unavailable for private ownership or are available for public use. As rights are country-based and vary, a work may be subject to rights in one country and not in another. Some rights depend on registrations with a country-by-country basis, and the absence of registration in a particular country, if required, implies public domain status in that country.
Definitions of the boundaries of the public domain in relation to copyright, or intellectual property more generally, regard the public domain as a negative space, that is, it consists of works that are no longer in copyright term or were never protected by copyright law. According to James Boyle this definition underlines common usage of the term public domain and equates the public domain to public property and works in copyright to private property. However, the usage of the term public domain can be more granular, including for example uses of works in copyright permitted by copyright exceptions. Such a definition regards work in copyright as private property subject to fair use rights and limitation on ownership. A conceptual definition comes from Lange, who focused on what the public domain should be: "it should be a place of sanctuary for individual creative expression, a sanctuary conferring affirmative protection against the forces of private appropriation that threatened such expression". Patterson and Lindberg described the public domain not as a "territory", but rather as a concept: "There are certain materials - the air we breathe, sunlight, rain, space, life, creations, thoughts, feelings, ideas, words, numbers - not subject to private ownership. The materials that compose our cultural heritage must be free for all to use no less than matter necessary for biological survival." The term public domain may also be interchangeably used with other imprecise and/or undefined terms such as the "public sphere" or "commons", including concepts such as "commons of the mind", the "intellectual commons", and the "information commons".
The term public domain did not come into use until the mid-17th century, although as a concept "it can be traced back to the ancient Roman Law, as a preset system included in the property right system." The Romans had a large proprietary rights system where they defined "many things that cannot be privately owned" as res communes, res publicae and res universitatis. The term res commune was defined as "things that could be commonly enjoyed by mankind, such as air, sunlight and ocean." 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. When looking at the public domain from a historical perspective, one could say the construction of the idea of "public domain" sprouted from the concepts of res commune, res publicae, and res universitatis in early Roman Law.
When the first early copyright law was first 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 eighteenth 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. The phrase "fall in the public domain" can be traced to mid-nineteenth century France to describe the end of copyright term. The French poet Alfred de Vigny equated the expiration of copyright with a work falling "into the sink hole of the public domain" and if the public domain receives any attention from intellectual property lawyers it is still treated as little more than that which is left when intellectual property rights, such as copyright, patents, and trademarks, expire or are abandoned. In this historical context Paul Torremans describes copyright as a "little coral reef of private right jutting up from the ocean of the public domain." Because copyright law is different from country to country, Pamela Samuelson has described the public domain as being "different sizes at different times in different countries".