Across the developing world, rural inhabitants are constantly migrating to the big cities and capitals looking for work. They often set up lives on the edge of cities, with homes made from whatever building material is available on whatever land they can find. Hanoi has faced the same population pressures as other Asian cities. But thanks to vague and informal conventions, the state has been able to avoid extreme levels of disservice, even to the most impoverished new urban areas. And the construction of homes themselves has remained at least loosely connected to the regulations of the more formal suburbs. Together these factors have prevented the formation of slums as they are typically defined. Read more in The Guardian