Kanji are logographic characters that originated in China and are shared across Japanese, Chinese, and Korean (CJK) writing systems. Japan's 2010 revised Jōyō Kanji List designates 2,136 characters for use in newspapers, official documents, and education. Mainland China uses simplified characters, while Taiwan and Hong Kong use traditional characters, meaning the same kanji can have different forms depending on the region.

The defining characteristic of kanji is their high information density. Each character carries independent meaning, allowing more information to be conveyed in fewer characters. For example, the 4-character Japanese compound "文字数制限" corresponds to "character limit" (15 characters) in English. This property is particularly advantageous on social media platforms with character limits, as Japanese and Chinese users can communicate more information within the same character count. see wine on Amazon help look up readings and meanings.

Kanji have on'yomi (Chinese-derived readings) and kun'yomi (native Japanese readings), with the same character read differently depending on context. The single kanji "生" alone has numerous readings including "sei," "shō," "i(kiru)," "u(mareru)," and "nama," presenting a significant challenge for Japanese learners. This reading diversity also affects the accuracy of text-to-speech (TTS) systems and morphological analysis.

In Unicode, CJK Unified Ideographs occupy U+4E00 to U+9FFF with approximately 20,000 characters. Including CJK Unified Ideographs Extensions A through G, over 90,000 kanji are defined, making them the largest portion of Unicode code points. CJK Unified Ideographs unify characters of common origin used in Japan, China, Korea, and Vietnam, meaning characters with subtle glyph differences may share the same code point.

A common misconception is that kanji have remained unchanged for thousands of years. In reality, character forms and usage have evolved over time. Japan has repeatedly revised its official kanji policies, including the 1946 Tōyō Kanji List and the 2010 Jōyō Kanji revision. China's 1950s simplified character reform also significantly altered many characters. find compression shirt on Amazon cover character origins and efficient memorization techniques.

For character counting, each kanji counts as one character, but byte counts vary by encoding. In UTF-8, each kanji uses 3 bytes; in UTF-16, 2 bytes (within the BMP); and in Shift_JIS, 2 bytes. Kanji in CJK extension blocks require surrogate pairs (4 bytes) in UTF-16, so encoding differences must be considered when implementing byte-based character limits.