The definition of "slum" varies from country to country. In India, The Slum Areas Improvement and Clearance Act of 1956 defines 'slum areas' as places where buildings: are in any respect unfit for human habitation; and are by reason of dilapidation, overcrowding, faulty arrangement and design of such buildings, narrowness or faulty arrangement of streets, lack of ventilation, light, sanitation facilities or any combination of these factors which are detrimental to safety, health and morals.
The Census of India defines a slum as "a compact area of at least 300 in population or about 60-70 households of poorly built, congested tenements in an unhygienic environment usually with inadequate infrastructure and lacking proper sanitary and drinking water facilities". The United Nations agency UN-HABITAT, defines slum as "a run-down area of a city characterized by substandard housing and squalor and lacking in tenure security".
Slums are an urban phenomenon and they represent an imbalance between migration into cities and economic growth within the city itself. They grow due to poor utilization of the reproductive child health services provided by the government, lack of awareness regarding birth spacing, very low use of contraceptives, illiteracy, and marriage at a young age. Another reason for growth of slums is migration from rural areas to more developed areas by people looking to earn more through higher-paying manual labor compared to the low-returns life of agriculture.
People living in slums face problems of housing, access to drinking water and sewage facilities. Residents live in overcrowded situations, a majority of them with dirt floors and poor ventilation which can lead to rapid spread of respiratory and skin disease. Also, the lack of safe drinking water facilitates the spread of water borne diseases. It is estimated that over one third of slum households have no access to bathroom and toilet