Urban area

An urban area is a human settlement defined by high population density. These areas feature a built environment, which is a landscape of human-made structures like buildings and roads.

Researchers use different terms to categorize these settlements. They may be called cities, towns, conurbations, or suburbs. In the study of urbanism, the term "urban area" is used to contrast with rural areas. Rural areas include small settlements like villages and hamlets.

In other fields, such as urban sociology, the term contrasts with the natural environment.

Urban areas grow through a process known as urbanization. This process involves the expansion of human settlements and the concentration of people.

One important distinction is between an urban area and a metropolitan area. An urban area serves as the central core of a metropolitan area. The metropolitan area includes the core urban area plus intervening rural land. It also includes satellite cities that are socio-economically connected to the core. These connections often happen through commuting for work.

In this relationship, the urban area acts as the primary labor market.

Defining the exact boundaries of an urban area can be difficult. Different organizations use different rules to measure them. For example, the Office for National Statistics defines built-up areas as land that is "irreversibly urban in character." This means the land looks like a town or a city. They consider areas linked if they are separated by less than 200 metres of non-urban space. In some less-developed countries, researchers also look at what people do for work. They may require that a large majority of the population does not work in agriculture or fishing.

The history of these settlements is very long. The urban revolution began during the 4th millennium BCE. This era led to the formation of human civilization. It also led to modern urban planning. As these areas grew, humans began the exploitation of natural resources. This human impact has changed the global environment.

Today, the scale of this change is visible from space.

Global population trends show a massive shift toward urban living. In 1950, 764 million people lived in urban areas. This was only about 30 percent of the world's 2.5 billion people. By 2009, the urban population reached 3.42 billion people. This was the first time urban dwellers outnumbered rural dwellers. By 2014, the urban population was 3.9 billion, or 53 percent of the 7.3 billion people on Earth.

The United Nations predicts that 68 percent of the world will live in urban areas by 2050. Most of this growth will happen in Africa and Asia.

Different countries show very different levels of urbanization. Argentina and Japan have urbanization rates higher than 90 percent. In the United States, the state of New Jersey has a rate of 100 percent. Other countries like Canada, Brazil, and Australia have rates between 80 and 90 percent.

China is a unique example of rapid growth. Since 2000, Chinese cities have expanded by about 10 percent every year. China has more cities with over one million residents than any other country.

Some urban areas are incredibly large and crowded. The Guangzhou-Shenzhen area in China has a population of over 69 million. The Tokyo-Yokohama area in Japan has over 37 million people.

In South Africa, cities are organized into metropolitan municipalities. These are the most developed areas and handle local government functions. In South Africa, five metros have more than four million residents. These large urban centers show how humans organize themselves across the globe.