Standard and literary Croatian is based on the central dialect, Shtokavian (stokavian), more specifically on Eastern Herzegovinian, which is also the basis of standard Serbian, Bosnian, and Montenegrin. The two other principal Croatian dialects are Chakavian (Cakavian) and Kajkavian.
These dialects, and the four national standards, are commonly subsumed under the term "Serbo-Croatian" in English, though this term is controversial for native speakersand paraphrases such as "Bosnian-Croatian-Montenegrin-Serbian" are therefore sometimes used instead, especially in diplomatic circles.
Vernacular texts in the Chakavian dialect first appeared in the 13th century, and Shtokavian texts appeared a century later. Standardization began in the period sometimes called "Baroque Slavism" in the first half of the 17th century, while some authors date it back to the end of 15th century.
The modern Neo-Shtokavian standard that appeared in the mid 18th century was the first unified Croatian literary language.