Korean is the official language of both North and South Korea. Korean is one of the world's oldest living languages, and its origins are is as obscure as the origin of the Korean people. Nineteenth Century Western scholars proposed a number of theories that linked the Korean language with Ural-Altaic, Japanese, Chinese, Tibetan, Dravidian Ainu, Indo-European and other languages. Korean is most likely a distant relative of the Ural-Altaic family of languages which includes such diverse languages as Mongolian, Finnish, and Hungarian. Linguistically, Korean is unrelated to Chinese and is similar to, but distinct from Japanese.

Early historical records indicate that at the dawn of the Christian era, two groups of languages were spoken in Manchuria and on the Korean Peninsula: the Northern or Puyo group and the southern or Han group. During the 7th Century, when the kingdom of Silla conquered the kingdoms of Paekche in southwest Korea and Koguryo in the north, the Silla dialect became the dominant language on the peninsula.

Following the emergence of the Koryo Dynasty in the 10th Century, the national capitol was moved to the city of Kaesong and the Kaesong dialect became the national language standard. The Choson Dynasty, founded at the end of the 14th Century, had its capital moved to Seoul. The new capital's geographic proximity to Kaesong however, did not lead to any significant changes in the language.

There are a number of regional dialects within Korea, defined mostly by the variations in stress placed on certain syllables and words from region to region. These dialects are loosely defined by provincial boundaries: Seoul (Kangwon and Kyonggi Provinces), Kyongsang Province, Cholla Province, Hamgyong Province, P'yong'an Province, Hwanghae Province, and Cheju Island. Except for the Cheju dialect, they are similar enough that Koreans have no trouble understanding each other.