Bulgaria (Bulgarian: България) officially the Republic of Bulgaria (Bulgarian: Република България) is a country in Southeastern Europe, and a member state of the European Union. It borders the Black Sea to the east, Greece and Turkey to the south, Serbia and the Republic of Macedonia to the west, and Romania to the north, mostly along the Danube. Bulgaria also shares a maritime border with Turkey, Romania, Ukraine, Russia, and Georgia. The capital of Bulgaria is Sofia.

Bulgaria is a country with an ancient history dating back to prehistoric times, the Thracian, Greek and Roman worlds of antiquity and the powerful Bulgarian Empire of the Middle Ages founded in 681. Geographically and climatically, Bulgaria is noted for its diversity, with the landscape ranging from the Alpine snow-capped peaks in Rila, Pirin and the Balkan Mountains to the mild and sunny weather of the Black Sea coast, from the typically continental Danubian Plain (ancient Moesia) in the north to the strong Mediterranean influence in the valleys of Macedonia and the lowlands in the southernmost parts of Thrace.

Bulgaria joined NATO on March 29, 2004 and the European Union on January 1, 2007. The country has been a member of the United Nations since 1955, and is a founding member of OSCE. As a Consultative Party to the Antarctic Treaty, Bulgaria takes part in the governing of the territories situated south of 60° south latitude.