Megacity: a city with more than 10 million inhabitants
Metropolis: an economic, cultural and political center of a large part of the world
Capital city: Usually the place where the government of a country resides
Facilities: places that provide specific goods or services, eg. supermarkets, swimming pools etc.
Economic sectors:
Primary sector: mining and agrarian business
Secondary sector: industry
Tertiary sector: services
Informal sector: Often unnecessary jobs that provide wages for people without formal education. These incomes are often unregistered.