Squatting consists of occupying an abandoned or unoccupied space or building

Building

In architecture, construction, engineering, real estate development and technology the word building may refer to one of the following:...

, usually residential, that the squatter does not own, rent or otherwise have permission to use.

Author Robert Neuwirth

Robert Neuwirth

Robert Neuwirth is an American journalist and author. He wrote Shadow Cities: A Billion Squatters, A New Urban World, a book describing his experiences living in squatter communities in Nairobi, Rio de Janeiro, Istanbul and Mumbai. His articles have appeared in the New York Times, The Nation, and...

 suggests that there are one billion squatters globally, that is, about one in every seven people on the planet. Yet, according to Kesia Reeve, "squatting is largely absent from policy and academic debate and is rarely conceptualized, as a problem, as a symptom, or as a social or housing movement."
In many of the world's poorer countries, there are extensive slum

Slum

A slum, as defined by United Nations agency UN-HABITAT, is a run-down area of a city characterized by substandard housing and squalor and lacking in tenure security. According to the United Nations, the percentage of urban dwellers living in slums decreased from 47 percent to 37 percent in the...

s or shanty town

Shanty town

A shanty town is a slum settlement of impoverished people who live in improvised dwellings made from scrap materials: often plywood, corrugated metal and sheets of plastic...

s, typically built on the edges of major cities

City

A city is a relatively large and permanent settlement. Although there is no agreement on how a city is distinguished from a town within general English language meanings, many cities have a particular administrative, legal, or historical status based on local law.For example, in the U.S...

 and consisting almost entirely of self-constructed housing built without the landowner's permission.