Shanty towns, also known as squatter settlements, have emerged in many large cities in developing countries due to large numbers of people migrating from rural to urban areas. They are characterized by makeshift housing built from scrap materials and lack adequate facilities. Common problems associated with shanty towns include diseases from poor sanitation, hazards from unstable housing, and social and political issues. Some governments have tried relocating residents but with limited success. Improved approaches involve communities in planning and building new housing.