Cities as systems of networks and flows
Cities are places where populations cluster to engage in economic exchange usually around a central market which represents an efficient point of distribution in a wider hinterland where various goods are produced. Although most cities still have well-defined central cores that function to tie economic and social activities together, the networks that sustain these cores are becoming ever more complex, diversified, and diffuse. Flows of people and commodities represent material interactions and tend to be more visible than electronic flows that occupy the ether which makes them much less visible. As these varieties of flow proliferate in a global world, the complexity of cities becomes ever greater and the challenge to our understanding ever more daunting. A consequence of complexity thinking is that cities get ever more complex as they grow. This is beyond complicatedness in that cities change qualitatively as they get larger and as their form adapts to embrace more and more human and physical interactions.