President

In the majority of republics, the term "president" refers to the head of state.
The obligations that a president is expected to perform vary according to the type of government in which he or she governs. Parliamentary republics tend to limit the obligations of the head of state, relegating them to purely ceremonial functions. In presidential and semi-presidential republics, the president's position is more prominent than in other forms of government, typically encompassing the chief executive's responsibilities in addition to the president's. Authoritarian regimes' presidents are also often referred to as dictators (although not usually openly within the dictatorship).
According on the circumstances, it is customary to address those in positions of authority as "Mister President" or "Madam President." It has historically functioned as the title for those who preside over legislative and judicial institutions, among other things.

Type

Civic, Political

Form of Address

Mister/Madam President