Among the different state constitutions (fundamental laws) that establish different political systems, four major types of heads of state can be distinguished: The parliamentary system, with three subset models; The standard model, in which the head of state, in theory, possesses key executive powers, but such power is exercised on the binding advice of a head of government (e.g. United Kingdom, India, Germany).
Printre diferitele constituții ale statului (legi fundamentale) care stabilesc sisteme politice diferite, se pot distinge patru tipuri majore de șefi de stat: Sistemul parlamentar, cu două modele: Modelul standard, în care șeful statului, teoretic, posedă puteri executive cheie, dar exercitarea unei asemenea puteri se face pe baza sfaturilor obligatorii ale șefului de guvern (de exemplu, Marea Britanie, India,Germania).