The law-making or legislative branch and administrative or executive branch and law enforcement and judicial branch and organizations of a society and from which issues and expresses, through law, in organized form, a state or a nation.
There are several forms of government, many having evolved in modern times only.
Tyranny and monarchy and, more recently, democracy are the traditional variations but even these have been tempered by constitutional limitations of the authority of a monarch, or the authority given to a president in a republic.
In addition, there are still socialist and communist government as well as those states, such as Arab states, which actively integrate religion and law-making.