The term "urban area" refers to a populated region that is characterized by a higher concentration of people, infrastructure and economic activity. There are a variety of words that can be used as synonyms for the term "urban area". Some of these include "metropolis", "cityscape", "conurbation", "megacity", "megalopolis", "cosmopolitan", "townscape", "downtown", "central business district", and "built-up area". These words reflect different aspects of urbanism, from the density of population to the architecture and infrastructure of cities. Regardless of which term is used, the concept of an urban area remains central to understanding modern society and its challenges.