A slum, as defined by United Nations Habitat, is a household that may suffer one or more of the following conditions: lack of access to water protected from outside contamination, lack of access to sanitation facilities that separate human waste from human contact and lack of adequate living area (more than three people living in one room of four square meters minimum). These conditions also include a lack of housing durability (the structure must be on non-hazardous land and must be able to withstand extremes in climate) and a lack of security of tenure (protection by the state to ensure the unlawful eviction of inhabitants of homes).
For the first time in history, more than half of the world’s population lives in cities. However, urban areas only account for three percent of the earth’s land. Over 90 percent of urban growth is occurring in developing nations. The increase of people living in cities can predictably rise to 60 percent in 2030 and to 66 percent by 2050.