Vuk St. Karadžić (1787-1864) is by all means the most prominent figure of the 19th century Serbian culture and one of the most prominent figures of Serbian history. The significance of his contribution is difficult to grasp in full due to variety of his activities and engagements, on the one hand, and  the impact of his reforms of Serbian language, which had both cultural and political implications, on the other.
In an attempt to make systematic overview of his contribution two distinct, but complementary lines of activity, as well as number of other activities, can be traced. 
a. The first line of activity is related to the reform of Serbian orthography. From a non-systematic and, to a large extent, chaotic Serbian language orthography of the 18th and the first part of the 19th century, Karadžić introduced radical reforms with long-term consequences. Karadžić established a phonemic orthography where a single grapheme corresponds to a single phoneme. This seemingly simple principle implies deep insights about the nature of a phoneme, i.e. the minimal distinct unit of meaning. After identifying 30 phonemes of Serbian language, Karadžić restricted Serbian alphabet to 30 corresponding graphemes. In 1812 he wrote the first Serbian primer (»Pismenica«) based on the new orthography and in 1818 he compiled and published first dictionary of Serbian language, also written in the new orthography.
b. The other line of Karadžić's activity is tied to the standardization of Serbian literary language. Serbian literature of the 18th and the beginning of the 19th century was not only written in an unstandardized orthography, but also in a unstandardized language that was spoken by small number of  upper class and educated people. Breaking radically with this tradition, Karadžić introduced the national language as a literary standard. For this language he wrote grammar and dictionary.
c. In addition to these two main lines of activities, Karadžić made great contribution to Serbian historiography (writing a history of the First Serbian uprisal), founded Serbian ethnology (collected Serbian proverbs and narodni običaji), translated the New Testament into Serbian and collected Serbian national poems and stories. 
d. In addition, the historical significance of Vuk St. Karadžić was in his successful attempts to make closer contacts between Serbia (at that time under Turkish occupation) and Europe. Through his contacts and collaboration with J. W. Goethe, G. Grimm, L. Ranke and other prominent scholars of that period, Karadžić introduced Serbian national poems and culture into Europe. Serbian national poems were translated into almost all European languages (....)
This short overview of his activities unveils the reasons why Karadžić's works were incorporated in full into the Corpus. His complete works encompass all significant periods in creation of standardized Serbian language and orthography. On the other hand, they allow for comparisons between the national and literary languages prior to his reforms. Finally, they enable contrasts between the language of Karadžić himself (i.e. through his correspondence) and various forms of the contemporary Serbian language.