The interplay between modern information and communication technologies and wireless sensor networks allows cities to become smart cities. Goods, people and traffic flows can be managed in a decentralized and adaptive way. The tracking of energy consumption, infrastructure use and user behaviour enables the optimal planning of urban resources. The local production and distribution of food reduces transport routes and thereby CO2 emissions. A smart power grid is also an important aspect in this urban system. What’s more, the connection and communication of city dwellers is supported by platforms that allow people to share their knowledge and information.