Cities are now home to half of humankind. They are the hub for much national production and consumption—economic and social processes that generate wealth and opportunity. But they also are places of disease, crime, pollution and poverty. In many cities in developing countries, slum-dwellers number more than 50 per cent of the population and have little or no access to shelter, water and sanitation. The UN Human Settlements Programme (UN-Habitat), with hundreds of projects in some 70 countries, seeks innovative solutions for towns and cities. These include providing security of tenure for the urban poor, which is in turn a catalyst for investment in housing and basic services for the poor.