Southeast Europe or Southeastern Europe (SEE) is a geographical subregion of Europe, consisting primarily of the Balkans, as well as adjacent regions and archipelagos. Sovereign states and territories that are included in the region are Albania, Bosnia and Herzegovina, Bulgaria, Croatia (alternatively placed in Central Europe), Cyprus (alternatively placed in West Asia), Greece (alternatively placed in the broader region of Southern Europe), Kosovo, Montenegro, North Macedonia, Romania, Serbia, and the European part of Turkey (alternatively placed in the broader region of Southern Europe, also in Western Asia with the rest of the country). Sometimes, Moldova (normally placed in Eastern Europe) and Slovenia (normally placed in Central Europe) are also included. The largest cities of the region are Istanbul, Athens, Bucharest, Sofia, and Belgrade.
There are overlapping and conflicting definitions of the region, due to political, economic, historical, cultural, and geographical considerations.
The first known use of the term "Southeast Europe" was by Austrian researcher Johann Georg von Hahn (1811–1869) as a broader term than the traditional Balkans, a concept based on the boundaries of the Balkan Peninsula (the countries that have been described as being entirely within the Balkan region are: Albania, Kosovo, Bosnia and Herzegovina, Bulgaria, Montenegro, and North Macedonia).
In recent years however, in part due to the historical and political connotations of the term Balkans, especially since the military conflicts of the 1990s in Yugoslavia in the western half of the region, the term Southeast Europe is becoming increasingly popular.
The German Ständige Ausschuss für geographische Namen (Standing Committee on Geographical Names), which develops and recommends rules for the uniform use of geographical names, proposes two sets of boundaries. The first follows international borders of current countries. The second subdivides and includes some countries based on cultural criteria. The following countries are included in their classification "Southeastern Europe":
In this classification, Slovenia and Croatia are included in Central Europe, Greece and Moldova in Southeastern Europe, and Turkey (East Thrace) outside of main Europe.
In the CIA World Factbook, the description of each country includes information about "Location" under the heading "Geography", where the country is classified into a region. The following countries are included in their classification "Southeast Europe":
In this classification, Slovenia is included in Central Europe, Greece in Southern Europe, and Moldova in Eastern Europe.