The commons are a model that places the management of natural and social resources in the hands of the user community, as opposed to having them managed by the market and the state. Around the world, throughout history as well as today, there have been numerous examples of such managing models for lakes, forests, pastures, airports, buildings, parks, gardens, digital encyclopaedia and computer programs. Institutions structured by user communities ensure fair access to a resource, collective control over its management and sustainable use of the resource. IPE explores and popularizes the existing models of shared resources management, and proposes new models for joint management of resources to ensure environmental sustainability and social justice.