The state of Bulgaria, officially the Republic of Bulgaria has formed a significant part of the Balkans in south-eastern Europe for many centuries. The state of Bulgaria borders five other countries. Romania to the north, Serbia and the Republic of Macedonia to the west, and Greece and Turkey to the south. The Black Sea defines the extent of the country to the east.
Bulgaria functions as a parliamentary democracy under a unitary constitutional republic. Bulgaria has been a member of the European Union since 2007. It has been a member of NATO since 2004, and has a population of approximately 7.6 million.