Urban life depends on sharing. We share spaces, we share buildings, we share facilities. We do this because we benefit from pooling all sorts of resources with others. This is not always straightforward, as individuals and groups have different priorities. However, there are many things that can only be done by a continual negotiation of these differences. This is the nature of cities.

Cities offer us a huge range of shared ‘public goods’: streets, squares, and parks; but not just spaces, also utilities such as water, electricity, and telephone/internet; and human services such as healthcare, security, and entertainment. We then make use of these in our different roles as individuals, families, communities, employees, entrepreneurs, homeowners, tenants. etc.

We string together the different parts of our lives along these infrastructural paths. We agree to maintain and develop them because they benefit everyone, and because they provide services and opportunities that often could not be provided in any other way. The more people use them the more efficient they get. So we could say that if cities had a colour, that colour would be yellow.