The world is undergoing a process of rapid urbanization - the movement of population from rural to urban areas. This is very important because it means that an increasing share of the world's population now live in cities The UN estimated in 2007 that half (50%) the world population now lives in cities and maybe 70%+ by the end of this century. This is a dramatic change from the world of our ancestors which was still overwhelmingly rural. The urban population was still only 30% of the world total in 1950. In China the process has been extremely rapid going from about 15% urban in 1950 to 65%+ in 2025. 75 years ago 85% of China's population lived in rural areas. But although urbanization has speeded up rapidly in recent decades it started a long time ago. It really took off in Britain about 1800 at the start of the industrial revolution During the c19th the population of London rose from 1 million in 1801 to 6.5 million in 1901 and the population of Birmingham, Manchester, Leeds, Glasgow and other industrial cities rapidly exploded. A similar process took place in the USA in the late c19th and early C20th as cities like New York, Chicago, Pittsburgh and Detroit rapidly expanded. In Europe cities like Paris and Berlin also grew rapidly. But today the rapid urban growth is in the developing world, the Global South, particularly in sub-Saharan Africa, Latin America and Asia where giant mega cities are emerging of over 20 million people cities like Beijing, Shanghai, Delhi, Mexico City and Cairo. Dhaka and Sao Paulo. It is estimated that by 2035 Africa will have 6 cities of over 10 million people with another 17 cities of over 5 million and 100 cities of over 1 million. Africa is the world most rapidly urbanizing region with cities like Dar es Salaam, Kinshasa, Luanda and Addis Ababa among the most rapidly growing. The problem is that while many rural migrants are attracted to the cities by a prospect of jobs, higher income and education, the reality is often very limited. In many rapidly growing there are major problems over the supply of drinking water, sewage and accommodation, and transport systems are often poor or non existent, with residents living 2 hours journey outside the city bycrowded minibus. The continuing urbanization of the world's population offers possibilities and many problems