Standard Slovene is the national standard language that was formed in the 18th century, mostly based on Upper and Lower Carniolan dialect groups, the latter being a dialect spoken by Primož Trubar. 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.
Slovene is an Indo-European language belonging to the Western subgroup of the South Slavic branch of the Slavic languages, together with Serbo-Croatian. It is close to the Chakavian and especially Kajkavian dialects of Serbo-Croatian, but further from the Shtokavian dialect, the basis for the Bosnian, Croatian, Montenegrin, and Serbian standard languages. Furthermore, Slovene shares certain linguistic characteristics with all South Slavic languages, including those of the Eastern subgroup, such as Bulgarian.
Although Slovene is almost completely intelligible with the Kajkavian dialects of Serbo-Croatian (especially the variant spoken in Hrvatsko Zagorje on the border with Slovenia), mutual intelligibility with other varieties of Serbo-Croatian is hindered by differences in vocabulary, grammar, and pronunciation. The Slovene language also has many commonalities with the West Slavic languages.