slum

Slum is a term used for an urban settlement in which residents live in substandard housing and have limited access to safe water, sanitation, electricity, and durable shelter. Slums are typically crowded, with insecure tenure, poor structural quality, and insufficient infrastructure. They arise in many developing cities as a result of rapid urban growth, poverty, inadequate housing supply, and exclusion from formal land and housing markets.

Common characteristics include high population density, inadequate housing quality, reliance on informal services, unsafe or congested streets, and vulnerability to fires, floods, and other hazards. Residents often lack formal property rights and face barriers to mortgage credit and formal infrastructure connections.

Causes are complex and interconnected: rural-to-urban migration, unemployment, rising land values, insufficient affordable housing, weak urban planning, and governance gaps. Slums are frequently located on marginal land or hazard-prone sites and may be neglected by formal service networks.

Impacts include adverse health outcomes (waterborne and respiratory diseases), poor nutrition, limited educational attainment, and social exclusion. Upgrading strategies focus on improving housing quality and access to services, securing tenure, and enhancing urban infrastructure, often through participatory planning and community involvement. Relocation is generally a last resort.

Terminology varies: some prefer "informal settlements" or "unplanned housing" to reduce stigma. Global experience shows slums are a widespread feature of many cities in Africa, Asia, and Latin America, with measurements depending on definitions and data sources.