The shapes of the consonants are based on the shape the mouth makes when the corresponding sound is made, and the traditional direction of writing (vertically from right to left) most likely came from Chinese, as did the practice of writing syllables in blocks.
Even after the invention of the Korean alphabet, most Koreans who could write continued to write either in Classical Chinese or in Korean using the Gukyeol or Idu systems. The Korean alphabet was associated with people of lower status, i.e., women, children and the uneducated. During the 19th and 20th centuries, a mixed writing system combining Chinese characters (Hanja) and Hangeul became increasingly popular. Since 1945 however, the importance of Chinese characters in Korean writing has diminished significantly. Since 1949 hanja have not been used at all in any North Korean publications, with the exception of a few textbooks and specialized books. In the late 1960s, however, hanja teaching was reintroduced in North Korean schools and school children are expected to learn 2,000 characters by the end of high school. In South Korea, school children are expected to learn 1,800 hanja by the end of high school. The proportion of hanja used in Korean texts varies greatly from writer to writer and there is considerable public debate about the role of hanja in Korean writing.
Most modern Korean literature and informal writing is written entirely in hangeul, however academic papers and official documents tend to be written in a mixture of hangeul and hanja.