They are usually defined as a state political entities that manage sovereign territory, and government organizations. The state appears when a government exercises its authority over a population inhabiting a given territory. This notion allows to classify the forms of state in accordance with the individual or body which exercises control. It is also distinguished various forms of State in accordance with the territorial distribution of that power. According to the body that exercises can be monarchy, when the government is in the hands of one person who usually inherits the hierarchy for life, or Republican, when exercised by several people with a mandate limited in time. The aristocratic republics are those in which the authority is represented by a small group of individuals, while the democratic rulers are elected by the entire population.
There are two broad classes of state. One is the unit in which power is concentrated in a single place in the territory, and the other is federal, with the coexistence of a central government and local authorities located in different parts of the country. The relationship between central and local, as well as the degree of autonomy of them, vary with the constitutions of the several States.