The modern Macedonian language belongs to the eastern sub-branch of the South Slavic branch of the Slavic branch of the Indo-European family of languages. The closest relative of Macedonian is Bulgarian, with which it is mutually intelligible. Following that, the next closest languages are Serbian, Bosnian and Croatian. Macedonian and its neighbours form a dialect continuum, with the Bulgarian standard based on the more eastern dialects and Macedonian based on the more western ones. It also includes the Torlakian dialect group that is intermediate between Bulgarian, Macedonian and Serbia, comprising some of the northernmost dialects of Macedonian as well as varieties spoken in southern Serbia.
Together with its immediate Slavic neighbours, Macedonian also forms a constituent language of the Balkan Sprachbund, a group of languages which share typological, grammatical and lexical features based on geographical convergence, rather than genetic proximity. Its other principal members are Romanian, Greek and Albanian, all of which belong to different genetic branches of the Indo-European family of languages (Romanian is a Romance language, while Greek and Albanian each comprise their own separate branches). Macedonian and Bulgarian are the only Slavic languages that don't use noun cases (except for the vocative, and apart from some traces of once living inflections still found scattered throughout the languages). They are also the only Slavic languages with any definite articles (there are three: unspecified, proximate and distal). This last feature is shared with Romanian, Greek, and Albanian.