CJK Unified Ideographs

The Chinese, Japanese and Korean (CJK) scripts share a common background, collectively known as CJK characters. In the process called Han unification, the common (shared) characters were identified and named "CJK Unified Ideographs." As of Unicode 9.0, Unicode defines a total of 80,388 CJK Unified Ideographs.

The terms ideographs or ideograms may be misleading, since the Chinese script is not strictly a picture writing system.

Historically, Vietnam used Chinese ideographs too, so sometimes the abbreviation "CJKV" is used. This system was replaced by the Latin-based Vietnamese alphabet in the 1920s.

The basic block named CJK Unified Ideographs (4E00–9FFF) contains 20,950 basic Chinese characters in the range U+4E00 through U+9FD5. The block not only includes characters used in the Chinese writing system but also kanji used in the Japanese writing system and hanja, whose use is diminishing in Korea. Many characters in this block are used in all three writing systems, while others are in only one or two of the three. Chinese characters were also used in Vietnam's Nôm script (now obsolete). The first 20,902 characters in the block are arranged according to the Kangxi Dictionary ordering of radicals. In this system the characters written with the fewest strokes are listed first. The remaining characters were added later, and so are not in radical order.

The block is the result of Han unification, which was somewhat controversial in the Far East. Since Chinese, Japanese and Korean characters were coded in the same location, the appearance of a selected glyph could depend on the particular font being used. However, the source separation rule states that characters encoded separately in an earlier character set would remain separate in the new Unicode encoding.

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