Sovereignty can generally be defined as supreme, independent control and lawmaking authority over a territory. It finds expression in the power to rule and make law. Sovereignty entails hierarchy within a state as well as external autonomy for states. In any state, sovereignty is assigned to the person, body or institution that has the ultimate authority over other people and to change existing laws. In political theory, sovereignty is a substantive term designating supreme legitimate authority over some polity. Under international law, sovereign states are all considered equal, and no state can interfere with the internal affairs of another sovereign state. While Article 2(7) of the UN Charter explicitly recognizes the sovereignty of states, and in general there is a principle of non-interference in the domestic affairs of sovereign states, the UN Security Council’s Chapter VII powers clearly contemplate the use of force against a state when necessary to restore peace. Further, the recent Responsibility to Protect (R2P) authorizes the United Nations to take action to “avert a humanitarian catastrophe” within a state when that state’s government cannot or will not act.

A state is generally considered to have sovereignty over a territory when it has consistently exercised state authority there without objection from other states. De jure sovereignty refers to the legal right to do so; de facto sovereignty refers to the factual ability to do so. This can become an issue of special concern upon the failure of the usual expectation that de jure and de facto sovereignty exist at the place and time of concern, and reside within the same organization.

The term arises from the unattested Vulgar Latin *superanus (itself a derived form of Latin super – "over") meaning "chief", "ruler". Its spelling, which has varied since the word's first appearance in English in the 14th century, was influenced by the English word "reign".

The concept of sovereignty has had multiple conflicting components, varying definitions, and diverse and inconsistent applications throughout history. The current notion of state sovereignty contains four aspects: territory, population, authority and recognition. According to Stephen D. Krasner, the term could also be understood in four different ways:

Often, these four aspects all appear together, but this is not necessarily the case – they are not affected by one another, and there are historical examples of states that were non-sovereign in one aspect while at the same time being sovereign in another of these aspects. According to Immanuel Wallerstein, another fundamental feature of sovereignty is that it is a claim that must be recognized if it is to have any meaning:

Sovereignty is a hypothetical trade, in which two potentially (or really) conflicting sides, respecting de facto realities of power, exchange such recognitions as their least costly strategy.

There are two additional components of sovereignty that should be discussed, empirical sovereignty and juridical sovereignty. Empirical sovereignty deals with the legitimacy of who is in control of a state and the legitimacy of how they exercise their power. Tilly references an example where nobles in parts of Europe were allowed to engage in private rights and Ustages, a constitution by Catalonia recognized that right which demonstrates empirical sovereignty. As David Samuel points out, this is an important aspect of a state because there has to be a designated individual or group of individuals that are acting on behalf of the people of the state. Juridical sovereignty emphasizes the importance of other states recognizing the rights of a state to exercise their control freely with little interference. For example, Jackson, Rosberg and Jones explain how the sovereignty and survival of African states were more largely influenced by legal recognition rather than material aid. Douglass North identifies that institutions want structure and these two forms of sovereignty can be a method for developing structure.

For a while, the United Nations highly valued juridical sovereignty and attempted to reinforce its principle often. More recently, the United Nations is shifting away and focusing on establishing empirical sovereignty. Michael Barnett notes that this is largely due to the effects of the post Cold War era because the United Nations believed that to have peaceful relations states should establish peace within their territory. As a matter of fact, theorists found that during the post Cold War era many people focused on how stronger internal structures promote inter-state peace. For instance, Zaum argues that many weak and impoverished countries that were affected by the Cold War were given assistance to develop their lacking sovereignty through this sub-concept of "empirical statehood".