A slum, as defined by the United Nations Agency UN-HABITAT, is a run-down area of a city characterized by substandard housing and squalor and lacking in tenure security.

More tan a few definitions have been put forward for describing informal settlements and the Slum was originally used mainly in the phrase  meaning a back room and later back alley and the origin of this word is thought to come from the Irish phrase ‘ (pron. s’lum ae) meaning ‘exposed vulnerable place. A slum is an alley or street of  un clean or dirty, crowded houses built back-to-back to one another characterized by cheap standards of living. A slum can further be defined as a densely populated urban area which is characterized by a generally low standard of living.

Slums may also be known as shantytowns in India.  According to  United Nations Agency UN-HABITAT is defining a slum as substandard housing and squalor and lacking in tenure security.  And a UN Expert Group also created an operational definition of a slum as an area that combines to various extents the following characteristics like inadequate access to safe water, inadequate access to sanitation and other infrastructure, poor structural quality of housing, overcrowding and insecure residential status. It is true that in India  slum growth rate in Mumbai is greater than the general urban growth rate.