A number of polities have declared independence and sought diplomatic recognition from the international community as sovereign states, but have not been universally recognised as such. These entities often have de facto control of their territory. A number of such entities have existed in the past.

There are two traditional theories used to indicate how a sovereign state comes into being. The declarative theory (codified in the 1933 Montevideo Convention) defines a state as a person in international law if it meets the following criteria:

1. a defined territory
2. a permanent population
3. a government, and
4. a capacity to enter into relations with other states.

According to the declarative theory, an entity's statehood is independent of its recognition by other states. By contrast, the constitutive theory defines a state as a person of international law only if it is recognised as such by other states that are already a member of the international community.^[1][2]

Quasi-states often reference either or both doctrines in order to legitimise their claims to statehood. There are, for example, entities which meet the declarative criteria (with de facto partial or complete control over their claimed territory, a government and a permanent population), but whose statehood is not recognised by any other states. Non-recognition is often a result of conflicts with other countries that claim those entities as integral parts of their territory.^[3] In other cases, two or more partially recognised states may claim the same territorial area, with each of them de facto in control of a portion of it (for example, the Republic of China (Taiwan) and the People's Republic of China). Entities that are recognised by only a minority of the world's states usually reference the declarative doctrine to legitimise their claims.^[4]

In many situations, international non-recognition is influenced by the presence of a foreign military force in the territory of the contested entity, making the description of the country's de facto status problematic. The international community can judge this military presence too intrusive, reducing the entity to a puppet state where effective sovereignty is retained by the foreign power.^[5] Historical cases in this sense can be seen in Japanese-led Manchukuo^[6] or the German-created Slovak Republic and Independent State of Croatia before and during World War II. In the 1996 case Loizidou v. Turkey, the European Court of Human Rights judged Turkey for having exercised authority in the territory of Northern Cyprus.^[7]

There are also entities that do not have control over any territory or do not unequivocally meet the declarative criteria for statehood but have been recognised to exist as sovereign entities by at least one other state. Historically, this has happened in the case of the Holy See (1870–1929); Estonia, Latvia, and Lithuania (during Soviet annexation);^[8] and Palestine at the time of its declaration of independence in 1988. The Sovereign Military Order of Malta is currently in this position. See list of governments in exile for unrecognised governments without control over the territory claimed.

State practice relating to the recognition of a country typically falls somewhere between the declarative theory and constitutive theory approaches.^{[9][10][11][12][13]}

The criteria for inclusion on this list is limited to polities that claim sovereignty, lack recognition from at least one UN member state, and either:^[14][15]

• satisfy the declarative theory of statehood, or^[16][17]
• are recognised (constitutive theory) as a state by at least one UN member state.^[18]

There are 193 United Nations (UN) member states, while both the Holy See and Palestine have observer state status in the United Nations.^[19] However, some countries that fulfill the declarative criteria, are recognised by the large majority of other states and are members of the United Nations are still included in the list here because one or more other states do not recognise their statehood, due to territorial claims or other conflicts.

Some states maintain informal (officially non-diplomatic) relations with states that do not officially recognise them. Taiwan (the Republic of China) is one such state, as it maintains unofficial relations with many other states through its Economic and Cultural Offices, which allow regular consular services. This allows Taiwan to have economic relations even with states that do not formally recognise it. A total of 56 states, including Germany,^[20] Italy,^[21] the United States,^[22] and the United Kingdom,^[23] maintain some form of unofficial mission in Taiwan. Kosovo,^[24] Northern Cyprus,^[25] Abkhazia,^[26] Transnistria,^[26] the Sahrawi Republic,^[27] Somaliland,^[28] and Palestine^[29] also host informal diplomatic missions, and/or maintain special delegations or other informal missions abroad.

• Subnational entities and regions that function as de facto independent states, with the central government exercising little or no control over their territory, but that do not explicitly claim to be independent. Examples include Puntland in Somalia,^[122][123] the Gaza Strip in Palestine,^[124] the Kurdistan Region in Iraq,^[125] Rojava in Syria^[126] and the Wa State in Myanmar.^[127]
• Rebel groups that have declared independence and exert some control over territory, but that reliable sources do not describe as meeting the threshold of a sovereign state under international law. Examples include Ambazonia, the Houthi movement and the Southern Movement; see list of rebel groups that control territory for a more complete list of such groups.
• Those areas undergoing current civil wars and other situations with problems over government succession, regardless of temporary alignment with the inclusion criteria (e.g. by receiving recognition as state or legitimate government), where the conflict is still in its active phase, the situation is too rapidly changing and no relatively stable quasi-states have emerged yet.
• Those of the current irredentist movements and governments in exile that do not satisfy the inclusion criteria by simultaneously not satisfying the declarative theory and not having been recognised as a state or legitimate government by any other state.
• Entities considered to be micronations, even if they are recognised by another micronation. Even though micronations generally claim to be sovereign and independent, it is often debatable whether a micronation truly controls its claimed territory.^{[lower-alpha 3]} For this reason, micronations are usually not considered of geopolitical relevance. For a list of micronations, see list of micronations.
• Uncontacted peoples who either live in societies that cannot be defined as states or whose statuses as such are not definitively known.
• Some states can be slow to establish relations with new UN member states and thus do not explicitly recognise them, despite having no dispute and sometimes favorable relations. These are excluded from the list. Examples include Croatia^[129] and Montenegro.^[130]

• Community for Democracy and Rights of Nations
• Decolonization
• Diplomatic recognition
• Separatism
  • List of active autonomist and secessionist movements
    • List of active separatist movements recognized by intergovernmental organizations
• Territorial dispute
• Territorial integrity
• Unilateral declaration of independence
• Unrepresented Nations and Peoples Organization