Chakavian
Chakavian in its actual use is the least spoken Serbo-Croatian dialect, being spoken only by 12% Croats. It is now mostly reduced in southwestern Croatia along the eastern Adriatic: Adriatic islands, and sporadically in the mainland coast, with rare inland enclaves up to central Croatia, and minor enclaves in Austria and Montenegro. All areas of old contacts with Romance languages.
Serbo-Croatian
Serbo-Croatian (; / also called Serbo-Croat , Serbo-Croat-Bosnian (SCB), Bosnian-Croatian-Serbian (BCS), or Bosnian-Croatian-Montenegrin-Serbian (BCMS)) is a South Slavic language and the primary language of Serbia, Croatia, Bosnia and Herzegovina, and Montenegro. It is a pluricentric language with four mutually intelligible standard varieties.