CJK characters
Chinese is written almost exclusively in Chinese characters. It requires over 3,000 characters for general literacy, but up to 40,000 characters for reasonably complete coverage. Japanese uses fewer characters — general literacy in Japanese can be expected with 1,945 characters. The use of Chinese characters in Korea is becoming increasingly rare, although idiosyncratic use of Chinese characters in proper names requires knowledge (and therefore availability) of many more characters. However, even today, students in South Korea are taught 1,800 characters.
A Syllabic Dictionary of the Chinese Language
Williams' preface to "A Syllabic Dictionary of the Chinese Language " explains, "The number of characters in this work is 12,527, contained in 10,940 articles, and placed under 522 syllables, which follow each other alphabetically, aspirated syllables coming after the unaspirated. Those syllables which begin with "ts", on account of their number, are placed by themselves after "tw'an"" (1874: ix). The additional 1,587 characters are differently written variant characters. For instance, the standard character 醫 for "yī" "medical doctor" has 酉 "wine vessel" indicating medicinal wine, but the earlier variant character 毉 has 巫 "Chinese shaman" indicating shamanic healing.