City
A city is a human settlement of a substantial size. The term "city" has different meanings around the world and in some places the settlement can be very small. Even where the term is limited to larger settlements, there is no universally agreed definition of the lower boundary for their size. In a narrower sense, a city can be defined as a permanent and densely populated 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.
Historically, city dwellers have been a small proportion of humanity overall, but following two centuries of unprecedented and rapid urbanization, more than half of the world population now lives in cities, which has had profound consequences for global sustainability. Present-day cities usually form the core of larger metropolitan areas and urban areas—creating numerous commuters traveling toward city centres for employment, entertainment, and education. However, in a world of intensifying globalization, all cities are to varying degrees also connected globally beyond these regions. This increased influence means that cities also have significant influences on global issues, such as sustainable development, climate change, and global health. Because of these major influences on global issues, the international community has prioritized investment in sustainable cities through Sustainable Development Goal 11. Due to the efficiency of transportation and the smaller land consumption, dense cities hold the potential to have a smaller ecological footprint per inhabitant than more sparsely populated areas. Therefore, compact cities are often referred to as a crucial element in fighting climate change. However, this concentration can also have some significant harmful effects, such as forming urban heat islands, concentrating pollution, and stressing water supplies and other resources.
Meaning
Urban settlements
Common population definitions for an urban area range between 1,500 and 50,000 people, with most U.S. states using a minimum between 1,500 and 5,000 inhabitants. Some jurisdictions set no such criteria.National censuses use a variety of definitions – invoking factors such as population, population density, number of dwellings, economic function, and infrastructure – to classify populations as urban.
City
A city can be distinguished from other human settlements by its relatively great size, but also by its functions and its special symbolic status, which may be conferred by a central authority. The term can also refer either to the physical streets and buildings of the city or to the collection of people who dwell there and can be used in a general sense to mean urban rather than rural territory.According to the "functional definition", a city is not distinguished by size alone, but also by the role it plays within a larger political context. Cities serve as administrative, commercial, religious, and cultural hubs for their larger surrounding areas. The presence of a literate elite is often associated with cities because of the cultural diversities present in a city. A typical city has professional administrators, regulations, and some form of taxation to support the government workers. The governments may be based on heredity, religion, military power, work systems such as canal-building, food distribution, land-ownership, agriculture, commerce, manufacturing, finance, or a combination of these. Societies that live in cities are often called civilizations.
Population size, density
The degree of urbanization is a modern metric to help define what comprises a city: "a population of at least 50,000 inhabitants in contiguous dense grid cells ". This metric was "devised over years by the European Commission, OECD, World Bank and others, and endorsed in March by the United Nations... largely for the purpose of international statistical comparison". Typical working definitions for small-city populations start at around 100,000 people.In specific countries
, the definition of what constitutes a city varies between the states.In the United Kingdom, city status is awarded by the Crown and then remains permanent, with only two exceptions to this rule due to policy changes. A lack of official qualifying criteria results in some particularly small cities, notably St Davids with a population of 1,751.
Etymology
The word city comes from the, itself from the, meaning "citizenship" or "state". The related civilization come from the Latin root wikt:civitas, originally meaning 'citizenship' or 'community member' and eventually coming to correspond with wikt:urbs, meaning 'city' in a more physical sense. The Roman civitas was closely linked with the Greek polis—another common root appearing in English words such as metropolis.In toponymic terminology, names of individual cities and towns are called astionyms.
Geography
deals both with cities in their larger context and with their internal structure. Cities are estimated to cover about 3% of the land surface of the Earth.Site
Town siting has varied through history according to natural, technological, economic, and military contexts. Access to water has long been a major factor in city placement and growth, and despite exceptions enabled by the advent of rail transport in the nineteenth century, through the present most of the world's urban population lives near the coast or on a river.Urban areas as a rule cannot produce their own food and therefore must develop some relationship with a hinterland that sustains them. Only in special cases such as mining towns which play a vital role in long-distance trade, are cities disconnected from the countryside which feeds them. Thus, centrality within a productive region influences siting, as economic forces would, in theory, favor the creation of marketplaces in optimal mutually reachable locations.
Center
The vast majority of cities have a central area containing buildings with special economic, political, and religious significance. Archaeologists refer to this area by the Greek term temenos or if fortified as a citadel. These spaces historically reflect and amplify the city's centrality and importance to its wider sphere of influence. Today cities have a city center or downtown, sometimes coincident with a central business district.Public space
Cities typically have public spaces where anyone can go. These include privately owned spaces open to the public as well as forms of public land such as public domain and the commons. Western philosophy since the time of the Greek agora has considered physical public space as the substrate of the symbolic public sphere. Public art adorns public spaces. Parks and other natural sites within cities provide residents with relief from the hardness and regularity of typical built environments. Urban green spaces are another component of public space that provides the benefit of mitigating the urban heat island effect, especially in cities that are in warmer climates. These spaces prevent carbon imbalances, extreme habitat losses, electricity and water consumption, and human health risks.Internal structure
generally follows one or more basic patterns: geomorphic, radial, concentric, rectilinear, and curvilinear. The physical environment generally constrains the form in which a city is built. If located on a mountainside, urban structures may rely on terraces and winding roads. It may be adapted to its means of subsistence. And it may be set up for optimal defense given the surrounding landscape. Beyond these "geomorphic" features, cities can develop internal patterns, due to natural growth or to city planning.In a radial structure, main roads converge on a central point. This form could evolve from successive growth over a long time, with concentric traces of town walls and citadels marking older city boundaries. In more recent history, such forms were supplemented by ring roads moving traffic around the outskirts of a town. Dutch cities such as Amsterdam and Haarlem are structured as a central square surrounded by concentric canals marking every expansion. In cities such as Moscow, this pattern is still clearly visible.
A system of rectilinear city streets and land plots, known as the grid plan, has been used for millennia in Asia, Europe, and the Americas. The Indus Valley Civilization built Mohenjo-Daro, Harappa, and other cities on a grid pattern, using ancient principles described by Kautilya, and aligned with the compass points. The ancient Greek city of Priene exemplifies a grid plan with specialized districts used across the Hellenistic Mediterranean.
Urban areas
The urban-type settlement extends far beyond the traditional boundaries of the city proper in a form of development sometimes described critically as urban sprawl. Decentralization and dispersal of city functions has transformed the very meaning of the term and has challenged geographers seeking to classify territories according to an urban-rural binary.Metropolitan areas include suburbs and exurbs organized around the needs of commuters, and sometimes edge cities characterized by a degree of economic and political independence. Some cities are now part of a continuous urban landscape called urban agglomeration, conurbation, or megalopolis
History
The emergence of cities from proto-urban settlements, such as Çatalhöyük, is a non-linear development that demonstrates the varied experiences of early urbanization. The cities of Jericho, Aleppo, Byblos, Faiyum, Yerevan, Athens, Matera, Damascus, and Argos are among those laying claim to the longest continual inhabitation.Cities, characterized by population density, symbolic function, and urban planning, have existed for thousands of years. In the conventional view, civilization and the city were both followed by the development of agriculture, which enabled the production of surplus food and thus a social division of labor and trade. Early cities often featured granaries, sometimes within a temple. A minority viewpoint considers that cities may have arisen without agriculture, due to alternative means of subsistence, to use as communal seasonal shelters, to their value as bases for defensive and offensive military organization, or to their inherent economic function. Cities played a crucial role in the establishment of political power over an area, and ancient leaders such as Alexander the Great founded and created them with zeal.