Dialects of Serbo-Croatian
Kajkavian is spoken in North Croatia, including the capital Zagreb, as well as in a few enclaves in Austria, Hungary, and Romania. Though its speakers are ethnic Croats and Kajkavian is thus generally considered a dialect of Serbo-Croatian, it is closer to neighboring Slovene than it is to Chakavian or Shtokavian. The Kajkavian area of Croatia is bordered on the northwest by Slovene language territory. It is bordered on the east and southeast by Shtokavian dialects roughly along a line that was the former division between Civil Croatia and the Habsburg Military Frontier; in southwest along Kupa and Dobra rivers, it persisted in ancient (medieval) contact with Chakavian dialects.
Official language
When Croatia declared independence (1991) it defined its official language as Croatian, and Serbia likewise defined its official language as Serbian. Bosnia-Herzegovina defined three official languages: Bosnian, Croatian, and Serbian. From the linguistic point of view, the different names refer to national varieties of the same language, which is known under the appellation of Serbo-Croatian. It is said by some that the Bosnian government chose to define three languages to reinforce ethnic differences and keep the country divided.
The language used in Montenegro, traditionally considered a dialect of Serbian, became standardized as the Montenegrin language upon Montenegro's declaration (2006) of independence.