Like Global Public Goods, the notion of Common goods deals with the thinking about the production of value and scarcity. If there is no unique and definitive definition of the concept of common goods, however, they can be seen as « […] gifts of nature or produced and maintained goods, shared between users grouped within a “community”  of which size and nature can vary. They suppose the commitment of citizens and the definition of right to use, especially regarding traditional knowledge. Natural common goods, such as water, land, forest, sea and oceans or the living, are today object of an appropriation without precedent that, instead of preserving them, jeopardize the ecological equilibrium and the life of the populations that depends on it  ». Indeed, as Alain Lipietz recalls « […] a common good is a social relation. We can have public goods that are privately managed  ».
Thus, « the global commons’preservation […] can not be conceivable without intergovernmental agreements that also apply to communities. That’s why, the United Nations still remains the irreplaceable place for the definition of the commons  ».
Elinor Ostrom  is the author who made one of the major contributions on the commons when she shattered the Hardin’s Tragedy of the Commons model, which considers the commons only as available resources, meanwhile, in reality, they are pre-eminently places for negotiation (there are no commons without community), managed by individuals who communicate, and among them a part is not guided by immediate interest, but by a collective sense. She insists on the fact that there is no « reference list » or a unique definition of the commons: each one is the product of unique historical circumstances, of a local culture, of economic and ecological conditions , and they can be idiosyncratic, adds David Bollier .
– All the commons have the same function: « the natural commons are necessary to our survival, the social commons allow social cohesion and cultural commons are essential to manage in an autonomous way our personal life and passions  ».
– All the commons have architecture, that is to say they can be considered as complex systems within which many components are interacting with each other.
The notion of Commons is associated to a specific form of property and governance which is placing collective decisions of « communities » in the centre of the socio-economic game. The Commons are then places of expression for the society, and as a consequence, a place for the resolution of conflicts; or as Alain Lipietz adds: « common goods are not things, but social relations, or more exactly, the things to which they are related (…) and they are the reign of diversity  ». In other terms, the commons are « modes of creation, of management and of collective and democratic sharing based on reciprocity  ».
Face to the principal danger that are facing the commons today, that is to say their privatization and/or their commodification, Pierre Calame has drawn up a typology of four kinds of goods  and proposes a reflection on their governance.
« The spectrum of the commons is enormous », according to Alain Lipietz . Taking up of Bertrand Badie’ s works , we might consider that human rights are among the first of our common goods.
As a way of example, we can mention the « creative commons » licenses, the collective projects’editors that share documents on a common property regime, which guarantee the non-private appropriation, just like Wikipédia or Music Brainz.
Other people, like the website onthecommons, count among the commons « the gifts from nature such as the air, the oceans and wildlife, just as social and shared creations like bookstores, public spaces, creative works and scientific research ».
But also: the gene pool, the lakes, the forests, the electromagnetic spectrum, traditional knowledge, the atmosphere, the Internet, informatics techniques… or even the ecological crisis, the rise of digital networks, the economy of knowledge, the profound modification of production regimes, the redefinition of immaterial property rights…