Megacity

A megacity is an urban settlement with at least 10 million inhabitants under the United Nations’ common definition. Its population may span several municipalities and include extensive suburbs.

Urbanization: The increasing concentration of people in towns and cities through population growth and migration. Rural-to-urban migration and natural increase help megacities reach enormous populations.
Tokyo: Japan’s capital and the center of one of the world’s largest metropolitan regions. Tokyo illustrates how a highly connected metropolitan region can accommodate immense population density.
Global city: A city with major influence over international finance, trade, culture, or governance. A megacity is defined by population, while a global city is defined by its international influence.
Urban heat island: The tendency for built-up areas to be warmer than nearby rural areas. Dense construction and limited vegetation can intensify heat exposure across megacities.
Urban agglomeration: A continuous urban area formed by a central city and its physically connected suburbs. Megacity populations often include a continuous built-up area crossing municipal boundaries.
Delhi: India’s capital territory and the core of a rapidly expanding metropolitan region. Delhi shows how fast population growth strains housing, air quality, and transport.
Metropolis: A large, important city that serves as a regional center. Metropolis is a broader urban designation and does not require a 10-million population threshold.
Air pollution: The presence of harmful substances in the air at concentrations that threaten health or ecosystems. Traffic, industry, and energy use can expose large megacity populations to polluted air.
Urban sprawl: The outward expansion of low-density development across the edges of an urban area. Sprawl can enlarge a megacity’s footprint faster than its population grows.
Lagos: Nigeria’s largest city and a major economic center on the Gulf of Guinea. Lagos combines rapid growth with extensive informal housing and infrastructure demands.

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