City networks are the connections between cities.
These networks can be of different nature and of different importance. In modern conceptions of cities, these networks play an important role in understanding the nature of cities. City networks can be physical connections to other places, such as railways, canals or scheduled flights. City networks also exist in immaterial form, such as trade, global finance, markets, migration, cultural links, shared social spaces or shared histories. There are also networks of religious nature, in particular through pilgrimage.
The city itself is then regarded as the node where different networks run together. Some of these networks are more powerful than others, and networks of global finance are currently (2009) dominant. Some urban thinkers have argued that cities can only be understood if the context of the city's connections is understood.
It has been argued that city networks are a key ingredient of what defines a city, along with the number of people (density) and the particular way of life in cities.