Currently, community life occurs mostly in cities and urban settlements. In fact, since 2008, the majority of the world’s population lives in them, and this amount is expected to increase by 2050.
Cities can provide many economic benefits, agglomerating population and reducing unit costs to deliver public services such as water and sanitation, health, education, electricity, emergency services, and recreational areas, which increase the possibilities of economic development, innovation and social interaction 
Although to live in cities have the potential to impact positively on the social and cultural economic development of the communities, it can also be – and indeed in some cases are – tremendously unequal and segregating.
In an inevitably globalized world, knowing what challenges the cities address and how to face them is becoming increasingly vital. Besides, the cities may deliver a tremendous contribution by filling a gap in a more fragmented global governance.
 Polèse, 2009; Satterthwaite, 2010 citados en World Economic and Social Survey. 2013. https://goo.gl/W6CY1q