The future of humanity is urban, and the nature of urban space enables, and necessitates, sharing -- of resources, goods and services, experiences. Yet traditional forms of sharing have been undermined in modern cities by social fragmentation and commercialization of the public realm. In Sharing Cities, Duncan McLaren and Julian Agyeman argue that the intersection of cities' highly networked physical space with new digital technologies and new mediated forms of sharing offers cities the opportunity to connect smart technology to justice, solidarity, and sustainability. McLaren and Agyeman explore the opportunities and risks for sustainability, solidarity, and justice in the changing nature of sharing