When we study world politics and economics, and try to understand our place in the global system, most of us think in terms of states, and of ourselves as citizens of one or other of those states. Maps of the world show continents and regions divided by state frontiers, demarcating areas that come under the administration of different governments and separate systems of law. When we travel from one state to another, we usually have to show passports or other documents, and are reminded that we are in transit until we return to the state to which we ‘belong’.