A republic (Latin: res publica) is a form of government in which the country is considered a “public matter”, not the private concern or property of the rulers. The primary positions of power within a republic are not inherited, but are attained through democracy, oligarchy or autocracy. It is a form of government under which the head of state is not a hereditary monarch.In the context of American constitutional law, the definition of republic refers specifically to a form of government in which elected individuals represent the citizen body and exercise power according to the rule of law under a constitution, including separation of powers with an elected head of state, referred to as a constitutional republic or representative democracy.As of 2017, 159 of the world’s 206 sovereign states use the word “republic” as part of their official names – not all of these are republics in the sense of having elected governments, nor is the word “republic” used in the names of all nations with elected governments. While heads of state often tend to claim that they rule only by the “consent of the governed”, elections in some countries have been found to be held more for the purpose of “show” than for the actual purpose of in reality providing citizens with any genuine ability to choose their own leaders.The word republic comes from the Latin term res publica, which literally means “public thing,” “public matter,” or “public affair” and was used to refer to the state as a whole. The term developed its modern meaning in reference to the constitution of the ancient Roman Republic, lasting from the overthrow of the kings in 509 B.C. to the establishment of the Empire in 27 B.C. This constitution was characterized by a Senate composed of wealthy aristocrats and wielding significant influence; several popular assemblies of all free citizens, possessing the power to elect magistrates and pass laws; and a series of magistracies with varying types of civil and political authority.
Most often a republic is a single sovereign state, but there are also sub-sovereign state entities that are referred to as republics, or that have governments that are described as “republican” in nature. For instance, Article IV of the United States Constitution "guarantee[s] to every State in this Union a Republican form of Government". In contrast, the former Soviet Union, which described itself as being a group of “Republics” and also as a “federal multinational state composed of 15 republics”, was widely viewed as being a totalitarian form of government and not a genuine republic, since its electoral system was structured so as to automatically guarantee the election of government-sponsored candidates.
An empire is a sovereign state functioning as an aggregate of nations or people that are ruled over by an emperor or another kind of monarch. The territory and population of an empire is commonly of greater extent than the one of a kingdom.An empire can be made solely of contiguous territories, such as the Austro-Hungarian Empire or the Russian Empire, or of territories far remote from the homeland, such as a colonial empire. Aside from the more formal usage, the word empire can also refer colloquially to a large-scale business enterprise (e.g. a transnational corporation), a political organisation controlled by a single individual (a political boss), or a group (political bosses). The word empire is associated with such other words as imperialism, colonialism, and globalization. Empire is often used to describe a displeasure to overpowering situations.An imperial political structure can be established and maintained in two ways: (i) as a territorial empire of direct conquest and control with force or (ii) as a coercive, hegemonic empire of indirect conquest and control with power. The former method provides greater tribute and direct political control, yet limits further expansion because it absorbs military forces to fixed garrisons. The latter method provides less tribute and indirect control, but avails military forces for further expansion. Territorial empires (e.g. the Mongol Empire and Median Empire) tend to be contiguous areas. The term, on occasion, has been applied to maritime empires or thalassocracies (e.g. the Athenian and British empires) with looser structures and more scattered territories.