Present-day cities usually form the core of larger metropolitan areas and urban areas-creating numerous commuters traveling toward city centres for employment, entertainment, and education. Historically, city dwellers have been a small proportion of humanity overall, but following two centuries of unprecedented and rapid urbanization, more than half of the world population now lives in cities, which has had profound consequences for global sustainability. Their density facilitates interaction between people, government organizations, and businesses, sometimes benefiting different parties in the process, such as improving the efficiency of goods and service distribution. Cities generally have extensive systems for housing, transportation, sanitation, utilities, land use, production of goods, and communication. It can be defined as a permanent and densely settled place with administratively defined boundaries whose members work primarily on non-agricultural tasks. Left to right, from top: Westminster Palace in London Shibuya Crossing in Tokyo painting of Boulevard Montmartre in Paris by Camille Pissarro the Rocinha favela in Rio de Janeiro 6th Avenue in Manhattan spice market in Old Delhi Hong Kong and the São Paulo MetroĪ city is a human settlement of a notable size.
