Slovene ( or ), or alternatively Slovenian (; or ), is a South Slavic language, a sub-branch that is part of the Balto-Slavic branch of the Indo-European language family. It is spoken by about 2.5 million speakers worldwide (excluding speakers of Kajkavian), mainly ethnic Slovenes, the majority of whom live in Slovenia, where it is the sole official language. As Slovenia is part of the European Union, Slovene is also one of its 24 official and working languages. Standard Slovene Standard Slovene is the national standard language that was formed in the 18th and 19th century, based on Upper and Lower Carniolan dialect groups, more specifically on language of Ljubljana and its adjacent areas. The Lower Carniolan dialect group was the dialect used in the 16th century by Primož Trubar for his writings, while he also used Slovene as spoken in Ljubljana, since he lived in the city for more than 20 years. It was the speech of Ljubljana that Trubar took as a foundation of what later became standard Slovene, with small addition of his native speech, that is Lower Carniolan dialect Trubar's choice was later adopted also by other Protestant writers in the 16th century, and ultimately led to the formation of more standard language. The Upper dialect was also used by most authors during the language revival in the 18th and early 19th centuries, and was also the language spoken by France Prešeren, who, like most of Slovene writers and poets, lived and worked in Ljubljana, where speech was growing closer to the Upper Carniolan dialect group. Unstandardized dialects are more preserved in regions of the Slovene Lands where compulsory schooling was in languages other than Standard Slovene, as was the case with the Carinthian Slovenes in Austria, and the Slovene minority in Italy. For example, the Resian and Torre (Ter) dialects in the Italian Province of Udine differ most from other Slovene dialects. The distinctive characteristics of Slovene are dual grammatical number, two accentual norms (one characterized by pitch accent), and abundant inflection (a trait shared with many Slavic languages). Although Slovene is basically an SVO language, word order is very flexible, often adjusted for emphasis or stylistic reasons. Slovene has a T–V distinction: second-person plural forms are used for individuals as a sign of respect. Classification Slovene is an Indo-European language belonging to the Western subgroup of the South Slavic branch of the Slavic languages,