Slovakia (Slovak: Slovensko), officially the Slovak Republic (Slovak: Slovenská republika), is a country in Central Europe. It is bordered by the Czech Republic and Austria to the west, Poland to the north, Ukraine to the east and Hungary to the south. Slovakia's territory spans about 49,000 square kilometres (19,000 sq mi) and is mostly mountainous. The population is over 5 million and comprises mostly ethnic Slovaks. The capital and largest city is Bratislava. The official language is Slovak, a member of the Slavic language family.