Slums are usually characterised by high rates of poverty and unemployment. And are breeding centres for many social problems such as crime, drugs, alcoholism and despair. And in many poor countries they are also breeding centres for disease due to unsanitary conditions. Slums are different from ghettos because ghettos usually have one race.
In many slums especially in poor countries, people live in very narrow alleys that do not allow vehicles (like ambulance, firefighters) to pass. Garbage accumilates in huge quantities. In some slums people collect the city cans for a living, later recycling them for the money.
Many governments around the world have attempted to solve the problems of slums by clearing away old decrepid housing, and replacing it with modern usually high rise housing with much better sanitation. This process is usually called "Slum clearance". Slum clearances have however not usually been successful in reducing the social problems associated with slums. Because the residents of the new housing, usually still face poverty and unemployment.