In the study of political science the executive branch of government has sole authority and responsibility for the daily administration of the state bureaucracy. The division of power into separate branches of government is central to the democratic idea of the separation of powers .

In many countries the term "government" connotes only the executive branch. However, this ambiguity fails to differentiate between despotic and democratic forms of government. In authoritarian systems (such as a dictatorship or absolute monarchy, where the different powers of government are assumed by one person), the executive branch ceases to exist since there is no other branch with which to share separate but equal governmental powers.

The separation of powers system is designed to distribute authority away from the executive branch - an attempt to preserve individual liberty in response to tyrannical leadership throughout history. The executive officer is not supposed to make laws (the role of the legislature), or interpret them (the role of the judiciary). The role of the executive is to enforce the law as written by the legislature and interpreted by the judicial system.

Titles and positions of responsibility

There are two roles which the top leadership of the executive branch fulfills; that of Head of State, and Head of Government. The organizational structure of the executive branch will determine the relationship between the heads of state and government respectively. The Executive Branch also carries out laws.

In a presidential system the executive is at once the Head of State and the Head of Government. Countries that model their government after the United States of America have a Head of State compared to other systems. The President of the United States is best described as the head of state for his or her role as the government's chief ambassador. However there is no constitutional foundation for any head of government in the United States since the separation of powers divides governmental authority amongst the branches with checks and balances over one another. The President of the United States can have significant power over public opinion through personal abilities of persuasion, however this is the natural effect of the executive office.