The three branches of government in the United States include the executive, legislative and judicial, and the power of the nation is divided among them. This is called the separation of powers. Power is divided in this way so that no one branch of government would become too powerful, preventing government abuse and tyranny.
In addition to this separation of power, the system of checks and balances is embedded in the Constitution. This means that each branch exercises some control over the other two. For example, although the president is the commander-in-chief of the Armed Forces, only Congress can declare war.
The founders realized the necessity of this systems early on, moved by a common desire of the Enlightenment: to protect freedom and avoid tyranny. In practice, the separation of powers and the system of checks and balances keep the government stable, united and controlled.
