Hanja
Although a phonetic Korean alphabet, now known as Chosŏn'gŭl or Hangul, had been created by Sejong the Great, it did not come into widespread official use until the late 19th and early 20th century. Thus, until that time it was necessary to be fluent in reading and writing Hanja in order to be literate in Korean, as the vast majority of Korean literature and most other Korean documents were written in Literary Chinese, using Hanja as its primary script. Today, a good working knowledge of Chinese characters is still important for anyone who wishes to study older texts (up to about the 1990s), or anyone who wishes to read scholarly texts in the humanities. Learning a certain number of Hanja is very helpful for understanding the etymology of Sino-Korean words, and for enlarging one's Korean vocabulary. Today, Hanja are not used to write native Korean words, which are always rendered in Hangul, and even words of Chinese origin—"Hanja-eo" ()—are written with the Hangul alphabet most of the time, with the corresponding Chinese character often written next to it in order to prevent confusion with other characters or words with the same phonetics.
Korean language
Another lesser-known theory is the Dravido-Korean languages theory which suggests a southern relation. Korean and Dravidian languages share similar vocabulary, both languages are agglutinative, follow the SOV order, nominal and adjectives follow the same syntax, particles are post positional, modifiers always precede modified words are some of the common features. However, typological similarities such as these could have arisen by chance; for instance, if a given pair of languages were agglutinative, most of the other typological features like SOV order, post-positional particles, modifiers preceding modified words might have evolved to be similar by mere chance (this being the general trend observable in most known agglutinative languages). Comparative linguist Kang Gil-un proposes 1300 Dravidian Tamil cognates in Korean, which would significantly outnumber the number of Dravidian cognates he claims are found in Tungusic, Turkic or Ainu. Nevertheless, he suggests that among currently researchable languages, the Nivkh language is most closely related to Korean. Juha Janhunen argues that the Goguryeo language could have been an Amuric language related to today's Nivkh language.