Good day Aya,

In Africa, and specifically South Africa, we are very much ofey with the concept. In Asia it is called a "slum area". However, not exactly the same setup. Informal settlements are usually people that build a house with their own material on vacant land. In city enviornments it is usually illegal occupation of the land and often on land that is not suitable for housing, hence the reason why the land is still vacant. But traditional housing (Xhosa rondawel) in built out of mud and often built on communal land and not seen as informal housing. Informal housing is pretty much a concept that is used when referring to the opposite of formal housing built with "bricks and mortar". So, if you get a self-built house erected on legal property, but with corrigated iron sheets or wooden material (not bricks and mortar) without the permission/approval of a local authority, it would probably also be classified as informal house. I think th ecrucial elements in such a definition amongs others, should be self-built without formal plan and/or approval from local authority. I must say, I myself get confused with all the exceptions. I published an article on research gate under the title: "Squatting in comfort, the way out for the very poor", that might shed some light on your problem.