Historically citydwellers have been a small proportion of humanity overall, but today, following two centuries of unprecedented and rapid urbanization, half of the world population is said to live in cities. Present-day cities usually form the core of larger metropolitan areas and urban areas, creating numerous commuters traveling towards city centers for employment, entertainment, and edification.
The most populated city proper is Shanghai while the largest metropolitan areas also include the Greater Tokyo Area and Jabodetabek (Jakarta). The cities of Faiyum, Damascus, and Varanasi are among those laying claim to longest continual inhabitation.
A city is 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.
A variety of definitions, invoking population, population density, number of dwellings, economic function, and infrastructure, are used in national censuses to classify populations as urban. Common population definitions for a city range between 1,500 and 50,000 people, with most states using a minimum between 1,500 and 5000 inhabitants. However, some jurisdictions set no such minimums. 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 sometimes included in the definition. A typical city has professional administrators, regulations, and some form of taxation (food and other necessities or means to trade for them) to feed the government workers. (This arrangement contrasts with the more typically horizontal relationships in a tribe or village accomplishing common goals through informal agreements between neighbors, or through leadership of a chief.) The governments may be based on heredity, religion, military power, work projects 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.
The word city and the related civilization come, via Old French, from the Latin root civitas, originally meaning citizenship or community member and eventually coming to correspond with 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.