Definition - What does Slum mean?
A slum is defined as a heavily populated urban area that is characterized by poor quality housing, poverty and the poor living conditions that result. Most slums are lacking an adequate supply of clean water, proper sanitation services, reliable electricity, law enforcement and other basic necessities, although the size and other characteristics in slums differ from country to country.
Safeopedia explains Slum
There are varied causes for the creation and expansion of slums. One reason could be rapid rural to urban migration, which often results in poverty through lack of opportunities and the government's ability to manage the overwhelming urban population. Other reasons include natural disasters, poor housing planning, poor infrastructure, politics, social conflicts, or the development of an informal economy, which is unregistered or unlicensed.