Author Robert Neuwirth suggested in 2004 that there were one billion squatters globally. He forecasts there will be two billion by 2030 and three billion by 2050. Yet, according to Kesia Reeve, "squatting is largely absent from policy and academic debate and is rarely conceptualised, as a problem, as a symptom, or as a social or housing movement."
Squatting can be related to political movements, such as anarchist, autonomist, or socialist. It can be a means to conserve buildings or to provide housing.
In many of the world's poorer countries, there are extensive slums or shanty towns, typically built on the edges of major cities and consisting almost entirely of self-constructed housing built without the landowner's permission. While these settlements may, in time, grow to become both legalised and indistinguishable from normal residential neighbourhoods, they start off as squats with minimal basic infrastructure. Thus, there is no sewerage system, drinking water must be bought from vendors or carried from a nearby tap, and if there is electricity, it is stolen from a passing cable.
Besides being residences, some squats are used as social centres or host give-away shops, pirate radio stations or cafs. In Spanish-speaking countries, squatters receive several names, such as okupas in Spain, Chile or Argentina (from the verb ocupar meaning "to occupy"), or paracaidistas in Mexico (meaning "parachuters", because they "parachute" themselves at unoccupied land).
During the period of global recession and increased housing foreclosures in the late 2000s, squatting became far more prevalent in Western, developed nations. In some cases, need-based and politically motivated squatting go together. According to Dr. Kesia Reeve, who specialises in housing research, squatting by necessity is in itself a political issue, therefore also a "statement" or rather a 'response' to the political system causing it. "In the context of adverse housing circumstances, limited housing opportunity and frustrated expectations, squatters effectively remove themselves from and defy the norms of traditional channels of housing consumption and tenure power relations, bypassing the 'rules' of welfare provision."
Dutch sociologist Hans Pruijt separates types of squatters into five distinct categories:
Deprivation-based i.e., homeless people squatting for housing need
An alternative housing strategy e.g., people unprepared to wait on municipal lists to be housed take direct action (as discussed in the preceding paragraph)
Entrepreneurial e.g., people breaking buildings to service the need of a community for cheap bars, clubs etc.
Conservational i.e., preserving monuments because the authorities have let them decay
Political e.g., activists squatting buildings as protests or to make social centres