CJK Language Codes — Chinese, Japanese, and Korean

CJK Language Codes

Chinese, Japanese, and Korean (CJK) languages share some Unicode character ranges but have distinct language codes and unique localization requirements.

Chinese Language Tags

Chinese is complex because it uses two different scripts and has many regional variants:

Tag	Meaning
zh	Chinese (generic)
zh-Hans	Chinese, Simplified script
zh-Hant	Chinese, Traditional script
zh-CN	Chinese as used in mainland China
zh-TW	Chinese as used in Taiwan
zh-HK	Chinese as used in Hong Kong
zh-Hans-CN	Simplified Chinese, China
zh-Hant-TW	Traditional Chinese, Taiwan
zh-Hant-HK	Traditional Chinese, Hong Kong

Best practice: Use script subtags (Hans/Hant) rather than relying on region alone, because the script is the primary differentiator for content and font selection.

Japanese Language Tags

Tag	Meaning
ja	Japanese
ja-JP	Japanese, Japan
ja-Latn	Japanese in Latin script (romaji)

Japanese uses four scripts simultaneously: kanji (漢字), hiragana (ひらがな), katakana (カタカナ), and romaji (Latin). The default tag ja implies the standard mixed-script writing.

Korean Language Tags

Tag	Meaning
ko	Korean
ko-KR	Korean, South Korea
ko-KP	Korean, North Korea

While Hangul (한글) is the primary script, some contexts mix Hanja (Chinese characters). South and North Korean differ in vocabulary, spelling rules, and Romanization.

Font and Rendering Considerations

CJK fonts are significantly larger than Latin fonts (often 5-20 MB). Strategies include:

/* Use font-display: swap for CJK web fonts */
@font-face {
  font-family: "Noto Sans JP";
  font-display: swap;
  src: url("/fonts/NotoSansJP.woff2") format("woff2");
}

/* CSS font stacks for CJK */
:lang(ja) {
  font-family: "Noto Sans JP", "Hiragino Kaku Gothic Pro",
               "Yu Gothic", sans-serif;
}
:lang(zh-Hans) {
  font-family: "Noto Sans SC", "PingFang SC",
               "Microsoft YaHei", sans-serif;
}
:lang(ko) {
  font-family: "Noto Sans KR", "Apple SD Gothic Neo",
               "Malgun Gothic", sans-serif;
}

Line Breaking and Text Spacing

CJK text has different word-breaking rules. CSS properties like word-break, overflow-wrap, and text-spacing-trim are important for proper CJK typography.