The Croatian writing system, employing the Latin script, contains 30 letters. In addition to the Latin basic letters, it has additional letters with accents that are included as official letters, as well as digraphs, a combination of letters considered as one. It is written from left-to-right.
Historically, as a member of the Serbo-Croatian language designation, it is a South Slavic language that shares a very close history with other standard forms of Serbo-Croatian. The Serbo-Croatian language has roots in Old Church Slavonic. This was the religious language of the Slavic areas during the 11th century. Old Church Slavonic, besides being a religious language, began to be used as a spoken language as well, and eventually gave way to Serbo-Croatian somewhere between the 12th and 16th centuries.
In the 17th century, Croatia was semi-autonomous as a political State, but was ruled by two dynasties. They made attempts to solidify Croatia as a political, cultural, and linguistic entity and this helped to differentiate the Serbo-Croatian spoken in Croatia in comparison to the other Serbo-Croatian varieties. However, despite such efforts, a true Croatian standard had not yet emerged at this time.
Croatian began to take on more distinct characteristics during the Illyrian period in the 19th century. During this time, the lands in Croatia contained many speech communities who spoke dialects of Serbo-Croatian that were not yet standardized. This variety also led to an inconsistent spelling and writing system. Thus, there was a movement, called the Illyrian movement to unify the dialects and have a standardized spelling in Croatia so that it can become both a spoken and literary language, one being endowed with a distinguished identity and carrying prestige. With intellectual efforts being led by Ljudevit Gaj to assimilate the Latin alphabet into Croatian use, and other scholars advocating for Shtokavian as the basis of the Croatian standard, Croatian began to take shape into the standard language of Croatia.
While overall, differences may not seem to be that apparent to outsiders, in terms of the Serbo-Croatian speaking communities, differentiating between Croatian and the other varieties can become a hot-button issue, as national identity and ethnic affiliation are deeply tied into the language. This can be seen by actions such as the Declaration on the Status and Name of the Croatian Literary Language made in 1967 by Croatian intellectuals. Even in other Serbo-Croatian speaking countries where there is a sizable ethnic Croat population, ethnic Croats insist on the term Croatian for the language that they speak. As an example, Croats who reside in Bosnia do not call the variety that they use Bosnian, but prefer the term Croatian, as to differentiate themselves, their culture, and their languages from that of the Bozniaks.
Nowadays, Standard Croatian remains the official language of Croatia. Even though Serbo-Croatian is considered one language by many linguists, in those areas where there is a differentiation, Standard Croatian is also considered an official language alongside the other Serbo-Croatian varieties such as Bosnian, and Montenegrin. Thus, Standard Croatian as a language itself, remains an important piece of the puzzle in terms of conducting, understanding the culture, and interacting with the people in the Serbo-Croatian speaking countries, as the language is a reflection of the socio-political circumstances in the region.