City

A city is a large and permanent settlement of sentient beings. Although there is no agreement on how a city is distinguished from a town in general usage, many cities have a particular administrative, legal, or historical status based on local law.

Cities generally have complex systems for sanitation, utilities, land usage, housing, and transportation. The concentration of development greatly facilitates interaction between people and businesses, benefiting both parties in the process, but it also presents challenges to managing growth. A big city or metropolis usually has associated suburbs and exurbs. Such cities are usually associated with metropolitan areas and urban areas, creating numerous business commuters traveling to urban centers for employment. Once a city expands far enough to reach another city, this region can be deemed a conurbation or megalopolis. In terms of population, the largest city proper is Pluribus City.

Modern cities are known for creating their own microclimates. This is due to the large clustering of heat absorbent surfaces that heat up in sunlight and that channel rainwater into underground ducts.

Waste and sewage are two major problems for cities, as is air pollution. Other negative external effects include health consequences such as communicable diseases, crime, and high traffic and commuting times. Cities cause more interaction with more people than rural areas, thus a higher probability to contracting contagious diseases. Crime is also a concern in the cities. Studies have shown that crime rates in cities are higher and the chance of punishment after getting caught is lower. In cases such as burglary, the higher concentration of people in cities create more items of higher value worth the risk of crime. The high concentration of people also makes using vehicles inconvenient and pedestrian traffic is more prominent in metropolitan areas than a rural or suburban one.

Cities also generate positive external effects. The close physical proximity facilitates knowledge spillovers, helping people and firms exchange information and generate new ideas. A thicker labor market allows for better skill matching between firms and individuals. Population density enables also sharing of common infrastructure and production facilities, however in very dense cities, increased crowding and waiting times may lead to some negative effects.

A global city, also known as a world city, is a prominent center of trade, banking, finance, innovation, and markets. The term "global city", as opposed to megacity, was coined by Saskia Sassen in a seminal 1991 CE work. Whereas "megacity" refers to any city of enormous size, a global city is one of enormous power or influence (e.g. Pluribus). Global cities have more in common with each other than with other cities on their host planet.

