Public ownership is the idea that land and resources within a nation belong, ultimately, to the people of that nation, and therefore the government can either own, control or regulate the land or resources for the good of the entire population. This idea was taken to the extreme in certain socialist countries in the mid- to late 1900s, but it also forms the basis of much governmental action in countries with capitalist systems. The doctrine also has been applied to certain things outside the borders of existing nations, such as the seabed and space.
At the most recognizable and extreme end of the spectrum of public ownership is the idea that all natural resources in a country belong to the people as a whole and thus must be used for their collective benefit, rather than the benefit of some private owners of that resource. This led to the concept of nationalization of certain industries in countries such as the Union of Soviet Socialist Republics and the People’s Republic of China in the middle of the 20th century. The emergence of new capitalistic systems has reduced the incidence of this kind of nationalization, but it still persisted in certain places into the 21st century, such as in the Venezuelan oil industry.
The most ubiquitous form that public ownership takes in countries with capitalistic systems is the concept of eminent domain. This is the idea that because the land belongs to the country's people as a whole, the government can take that land for the benefit of the people, even if the private owners of the land do not consent. In most democracies, this taking must be accompanied by payment to the private owners of fair market value of the land, except in certain national emergencies. This power has been used, for example, in the United States for the building of public highways and other public works.
These types of public works are another form that the concept of public ownership can take. In the U.S., there is a national park system where large areas of wilderness are mostly protected from development for the use and enjoyment of the citizenry. Even smaller governmental entities, such as counties and cities, use this idea of public ownership when creating parks and recreational facilities for use by residents, maintained at public expense. Sometimes, the practice of the public ownership doctrine is not so tangible, however.
The U.S., for example, has created public corporations to operate railroads or to build infrastructure. In Great Britain, the British Broadcasting Company was created by Royal Charter for six different public purposes, including sustaining citizenship, sustaining civil society and promoting education and learning. These projects stem from the idea that the government serves as a steward of certain less tangible resources, such as transportation and communication, that are part and parcel of the concept of public ownership.
A more international form of public ownership proceeds from the old Roman concept of res extra commercium, which is the idea that certain resources are not amenable to private ownership. This has led to international agreements to keep certain areas out of the control of specific nations. Such places include the utilization of the seabed under the Earth’s oceans and the vast area of space that surrounds the planet.