Political demography is the study of the relationship between politics and population change. Population change is driven by classic demographic mechanisms – birth, death, age structure, and migration. However, in political demography, there is always scope for assimilation as well as boundary and identity change, which can redraw the boundaries of populations in a way that is not possible with biological populations. Typically, political-demographic projections can account for both demographic factors and transitions caused by social change.
Squatting is the action of occupying an abandoned or unoccupied area of land or a building, usually residential, that the squatter does not own, rent or otherwise have lawful permission to use. The United Nations estimated in 2003 that there were one billion slum residents and squatters globally. Squatting occurs worldwide and tends to occur when people who are poor and homeless find empty buildings or land to occupy for housing. It has a long history, broken down by country below.
In demographics, the world population is the total number of humans currently living. It was estimated by the United Nations to have exceeded eight billion in mid-November 2022. It took over 200,000 years of human prehistory and history for the human population to reach one billion and only 219 years more to reach 8 billion. The human population has experienced continuous growth following the Great Famine of 1315–1317 and the end of the Black Death in 1350, when it was nearly 370,000,000.
A city is a human settlement of a notable size. It can be defined as a permanent and densely settled place with administratively defined boundaries whose members work primarily on non-agricultural tasks. Cities generally have extensive systems for housing, transportation, sanitation, utilities, land use, production of goods, and communication. Their density facilitates interaction between people, government organizations, and businesses, sometimes benefiting different parties in the process, such as improving the efficiency of goods and service distribution.