Housing society is a term used to describe residential complexes usually consisting of buildings each having flats, especially in India. A housing society is a group of house owners generally residing in same building, apartments or same premises formed as per relevant laws for smooth functioning of utilities and other amenities provided to them. The housing society formed must be formally registered with registar of Co-operatives. Each state has its own rules in this regard. Each building in same premise may have separate housing society or one. Many housing societies form one federation. Housing societies run on the fees or charges levied by them on house or flat owners. Some of the housing societies in Mumbai are cash rich, having millions of rupees in their bank account.