Unless otherwise specified, Chinese text in this article is written in the format Simplified Chinese / Traditional Chinese, Pinyin. If the Simplified and Traditional Chinese characters are identical, they are written only once.
Chinese characters constitute the oldest continuously used system of writing in the world. By virtue of their widespread current use in East Asia, and historic use throughout the Sinosphere, Chinese characters are among the most widely adopted writing systems in the world by number of users.
In Japan, common characters are written in post-WWII Japan-specific simplified forms (shinjitai), while uncommon characters are written in Japanese traditional forms (kyūjitai), which are virtually identical to Chinese traditional forms. In South Korea, when Chinese characters are used, they are in traditional form, essentially identical to those used in Taiwan and Hong Kong where the official writing system is traditional Chinese. Teaching of Chinese characters in South Korea starts in the 7th grade and continues until the 12th grade; a total of 1,800 characters are taught, though these characters are used only in certain cases (on names, signs, academic papers, historical writings, etc.) and are slowly declining in use as native alphabetical hangul supplanted them in most aspects of Korean society.
In Old Chinese including Classical Chinese, most words were monosyllabic and there was a close correspondence between characters and words. In modern Chinese, the majority of Chinese words today consist of two or more characters. Rather, a character almost always corresponds to a single syllable that is also a morpheme.However, there are a few exceptions to this general correspondence, including bisyllabic morphemes (written with two characters), bimorphemic syllables (written with two characters) and cases where a single character represents a polysyllabic word or phrase.
Modern Chinese has many homophones; thus the same spoken syllable may be represented by many characters, depending on meaning. A single character may also have a range of meanings, or sometimes quite distinct meanings; occasionally these correspond to different pronunciations. Cognates in the several varieties of Chinese are generally written with the same character. They typically have similar meanings, but often quite different pronunciations. In other languages, most significantly today in Japanese and sometimes in Korean, characters are used to represent Chinese loanwords, to represent native words independently of the Chinese pronunciation (e.g., kunyomi in Japanese), and as purely phonetic elements based on their pronunciation in the historical variety of Chinese from which they were acquired. These foreign adaptations of Chinese pronunciation are known as Sino-Xenic pronunciations and have been useful in the reconstruction of Middle Chinese.
When the script was first used in the late 2nd millennium BC, words of Old Chinese were generally monosyllabic, and each character denoted a single word.
Increasing numbers of polysyllabic words have entered the language from the Western Zhou period to the present day.
It is estimated that about 25–30% of the vocabulary of classic texts from the Warring States period was polysyllabic, though these words were used far less commonly than monosyllables, which accounted for 80–90% of occurrences in these texts.
The process has accelerated over the centuries as phonetic change has increased the number of homophones.
It has been estimated that over two thirds of the 3,000 most common words in modern Standard Chinese are polysyllables, the vast majority of those being disyllables.
The most common process has been to form compounds of existing words, written with the characters of the constituent words.
Words have also been created by adding affixes, reduplication and borrowing from other languages.
Polysyllabic words are generally written with one character per syllable.[a]
In most cases the character denotes a morpheme descended from an Old Chinese word.
Many characters have multiple readings, with instances denoting different morphemes, sometimes with different pronunciations.
In modern Standard Chinese, one fifth of the 2,400 most common characters have multiple pronunciations.
For the 500 most common characters, the proportion rises to 30%.
Often these readings are similar in sound and related in meaning.
In the Old Chinese period, affixes could be added to a word to form a new word, which was often written with the same character.
In many cases the pronunciations diverged due to subsequent sound change.
For example, many additional readings have the Middle Chinese departing tone, the major source of the 4th tone in modern Standard Chinese.
Scholars now believe that this tone is the reflex of an Old Chinese *-s suffix, with a range of semantic functions.
传/傳 has readings OC *drjon > MC drjwen > Mod. chuán 'to transmit' and *drjons > drjwenH > zhuàn 'a record'. (Middle Chinese forms are given in Baxter's transcription, in which H denotes the departing tone.)
磨 has readings *maj > ma > mó 'to grind' and *majs > maH > mò 'grindstone'.
宿 has readings *sjuk > sjuwk > sù 'to stay overnight' and *sjuks > sjuwH > xiù 'celestial "mansion"'.
说/説 has readings *hljot > sywet > shuō 'speak' and *hljots > sywejH > shuì 'exhort'.
Another common alternation is between voiced and voiceless initials (though the voicing distinction has disappeared on most modern varieties).
This is believed to reflect an ancient prefix, but scholars disagree on whether the voiced or voiceless form is the original root.
见/見 has readings *kens > kenH > jiàn 'to see' and *gens > henH > xiàn 'to appear'.
败/敗 has readings *prats > pæjH > bài 'to defeat' and *brats > bæjH > bài 'to be defeated'. (In this case the pronunciations have converged in Standard Chinese, but not in some other varieties.)
折 has readings *tjat > tsyet > zhé 'to bend' and *djat > dzyet > shé 'to break by bending'.