cities:

with a high population density and a particular administrative, legal, or historical status.
Large industrialized cities generally have advanced systems for sanitation, utilities, land usage, housing, and transportation and more. This proximity greatly facilitates interaction between people and firms, benefiting both parties in the process. However, there is debate now whether the age of technology and instantaneous communication with the use of the Internet are making cities obsolete.[1][2]
A big city, or metropolis, may have suburbs and regions. Such cities are usually associated with metropolitan areas and urban sprawl, creating large numbers of business commuters. Once a city sprawls far enough to reach another city, this region can be deemed a conurbation or megalopolis.
The conventional view holds that cities first formed after the Neolithic revolution. The Neolithic revolution brought agriculture, which made denser human populations possible, thereby supporting city development (Bairoch 1988, p. 3-4). The advent of farming encouraged hunter-gatherers to abandon nomadic lifestyles and to choose to settle near others who lived off of agricultural production. The increased population density encouraged by farming and the increased output of food per unit of land, created conditions that seem more suitable for city-like activities. In his book, “Cities and Economic Development,” Paul Bairoch takes up this position as he provides a seemingly straightforward argument, which makes agricultural activity appear necessary before true cities can form.
According to Vere Gordon Childe, for a settlement to qualify as a city, it must have enough surplus of raw materials to support trade (Pacione 2001, p. 16). Bairoch points out that, due to sparse population densities that would have persisted in pre-Neolithic, hunter-gatherer societies, the amount of land that would be required to produce enough food for subsistence and trade for a large population would make it impossible to control the flow of trade. To illustrate this point, Bairoch offers “Western Europe during the pre-Neolithic, [where] the density must have been less than 0.1 person per square kilometer”