This thesis will present a historical overview of the standardization of the Croatian language up to the 20th century. At first, spatial characteristics of the Croatian language will be explained, namely all three of its dialects: Štokavian, Kajkavian and Chakavian, in order to better understand the historical developments related to the standardization process and the selection of the Štokavian basis of the Croatian standard language. Culture in today's Republic of Croatia rests on the foundations of three scripts: Glagolitic, Cyrillic and Latin. Thesis describes the written traces that were found and testify to these three letters that enriched the history of the Croatian language and the culture of the Croatian people as a whole. In the second part of this paper, the periodization of the Croatian language according to Brozović (1978) will be presented, which follows its development in six periods. This is followed by a presentation of Croatian lexicography, grammar and dictionaries of the 16th, 17th and 18th centuries. Dictionaries and grammars standardized the Croatian language of that time, which influenced further activities related to the standardization of the Croatian language until its completion at the beginning of the 20th century. The paper also explains the Croatian national revival together with the first newspapers written in the Croatian language, language issues in the Illyrian provinces, graphic issues in Dalmatia in the 19th century, but also the issue of Štokavian in Slavonia and Kajkavian on the eve of the Croatian national revival. The Illyrian movement, which together with the philological schools left its mark on the Croatian language and without which today's standard Croatian language would not exist in this form, is also connected with the Croatian national revival.