As defined by Max Weber (1864-1920) State is the institution which claims the exclusive right to the legitimate exercise of force in a given territory, through the use of police to enforce laws or the army to maintain civil stability.
A state is a set of institutions that possess the authority to make the rules that govern the people in one or more societies, having internal and external sovereignty over a definite territory. Institutions of the state include government and agencies like the army, police, judiciary, crown corporations, welfare bureaucracies, and regulatory bodies.
States are the subjects of public international law, also known as the "law of nations." Their existence and conduct is governed by treaties and customary rules. While there have been stateless societies, most complex societies have state systems of formal government and administrative bureaucracies.
In a federal system, the term state also refers to political units, not sovereign themselves, but subject to the authority of the larger state, or federal union, such as the "states" in the United States.
The Montevideo Convention of 1933 provides four criteria for achieving statehood: a permanent population, a defined territory, government and capacity to enter into relations with other states.