The most accepted theory among scientists claims that the Earth formed from the Big Bang, which was a great explosion of energy. The formation of the planet Earth would have occurred soon after the beginning of the formation of the Solar System. The probable date is about 5 billion years ago. There are assumptions that the solar system has formed from the aggregation of cosmic dust, warming up by the release of energy from the impact caused by the shock of the materials in fusion. The Earth was a glowing ball that had been cooling down over time.

^{"During the process of melting the materials that formed the Earth, the heavier and heavier elements (especially iron and nickel) moved to the deeper layers, while the lighter and less dense elements were close to the surface." SILVA, 2013, p.95)}
From this process there was the formation of the layers of the Earth. With the denser materials forming the core (inner and outer), the mantle (upper and lower) and the earth crust (upper and lower). The outer part of the Earth is called the lithosphere, which is where life develops. This layer was constituted from the consolidation of the incandescent material, and is basically formed by rocks.

During the process of cooling the Earth there was the release of gases and vapors, which gave rise to a layer of air surrounding the planet, called the atmosphere. The atmosphere is, therefore, the layer of gases that surround the planet Earth, made up of innumerable types of gases that are retained due to the Earth's gravity and magnetic field. The type of gases that were present changed over time, and in the origin of the planet there was the presence of methane, ammonia, nitrites, water vapors and carbon dioxide, whereas oxygen and nitrogen are now predominant, representing almost gases present in the atmosphere. These gases contribute to making life on Earth possible. Recalling that the Earth is composed of 78% of Nitrogen, 21% of Oxygen and 1% of other gases.

It is estimated that around 4.6 billion years ago, the Earth was in the process of cooling, causing an extensive period of rainfall, caused by the condensation of water vapor in the atmosphere. This rain has accumulated in the lower parts of the earth's surface, forming what we know as oceans. All the water existing on the Earth's surface constitutes the hydrosphere. The waters of the Earth are in constant renewal, from the hydrological cycle

The urban and rural spaces are inserted as different expressions materialized in the geographical space, understood by its different economic, cultural, technical and structural dynamics. Although they compose means considered distinct, their interrelationships are quite complex. Hence, it is often difficult to separate or understand the specificity of each of these concepts.

The concept of urban space designates the area of ​​high population density with formation of dwellings juxtaposed with each other, what we call a city. The concept of rural space refers to the set of primary activities practiced in areas not occupied by cities or large population densities.

However, beyond this simple and introductory definition, it is interesting to realize that rural and urban are, in addition, different types of daily practices. Thus, there may be rural practices in the space of cities or urban practices in the countryside. For example, a crop of vegetables within the space of a city (although this is increasingly rare in large urban centers) is a case of rural practice in urban areas. Similarly, the existence of a farmhouse or a resort in a remote area of ​​the city is an example of urban practice in the countryside.

One of the main differences between urban and rural is thus in socioeconomic practices. Rural space, as we have said, predominantly includes activities linked to the primary sector (extractivism, agriculture and livestock), while the urban space usually brings together activities linked to the secondary sector (industry and energy production) and tertiary (trade and services) .

Another difference between urban and rural is in the amplitude of the respective concepts. In terms of scale, the spatial scope of the rural environment is much larger, since it brings together so many areas transformed and cultivated (agrarian space) by man as the natural space, little transformed or maintained totally without anthropic interventions. On the other hand, the city, although it has a greater economic dynamics, presents itself in more circumscribed spaces, even with the disorderly growth of the urban spaces in the majority of peripheral and emerging countries.

In terms of economic hierarchy, we can say that, originally, the field had a preponderant role on the cities. After all, it was the development of agriculture and livestock that allowed the formation of the first civilizations and their subsequent development. However, with the advancement of the Industrial Revolution and the technical transformations it produced, the rural environment was increasingly subordinated to the urban, since agricultural and extractive practices became increasingly dependent on techniques, technologies and knowledge produced in cities.

More recently the industrial revolution and the Second World War were responsible for the intensification of urbanization processes.

If we imagine that man has dominated the fire for 500,000 years and sapiens has a history of 150,000 years and a cultural history of about 30,000 years, we can say that the formation of cities is a recent fact, especially when we take urbanization into account Brazil, which emerged after the 1940s.

Today, it is estimated that more than half the world's population is concentrated in cities.

Cities have already been the solution, the problem and today, it seems, cities are the opportunity. The opportunity for connection, exchange, support, prosperity, happiness.