Estonia, officially the Republic of Estonia, is a country in Northern Europe. It is bordered to the north by the Gulf of Finland across from Finland, to the west by the Baltic Sea across from Sweden, to the south by Latvia, and to the east by Russia. The territory of Estonia consists of the mainland, the larger islands of Saaremaa and Hiiumaa, and over 2,300 other islands and islets on the east coast of the Baltic Sea. Its capital Tallinn and Tartu are the two largest urban areas. The Estonian language, of the Finnic family, is the official language and the first language of the majority of its population of nearly 1.4 million. Estonia is one of the least populous members of the European Union and NATO.
Present-day Estonia has been inhabited since at least 9,000 BC. The medieval indigenous population of Estonia was one of the last pagan civilisations in Europe to adopt Christianity following the Northern Crusades in the 13th century. After centuries of foreign rule by the Teutonic Order, Denmark, Poland, Sweden, and the Russian Empire, a distinct Estonian national identity gained new momentum with the Age of Awakening in the mid-19th century. This culminated in the 1918 Estonian Declaration of Independence. Democratic throughout most of the interwar period, Estonia declared neutrality at the outbreak of World War II, but the country was repeatedly invaded and occupied, and ultimately annexed into the USSR. Throughout the de facto Soviet occupation, from World War II until 1991, Estonia's de jure state continuity was preserved by diplomatic representatives and the government-in-exile. Following the 1988–1990 "Singing Revolution" against Soviet rule, full independence was restored on 20 August 1991.
