Chinese characters have been used in several different
writing systems throughout history. The concept of a writing system includes both the written symbols themselves, called
graphemes—which may include characters, numerals, or punctuation—as well as the rules by which they are used to record language. Chinese characters are
logographs, which are graphemes that represent units of meaning in a language. Specifically, characters represent the smallest units of meaning in a language, which are referred to as
morphemes. Morphemes in Chinese—and therefore the characters used to write them—are nearly always a single syllable in length. In some special cases, characters may denote non-morphemic syllables as well; due to this,
written Chinese is often characterised as
morphosyllabic. Logographs may be contrasted with
letters in an
alphabet, which generally represent
phonemes, the distinct units of sound used by speakers of a language. Despite their origins in picture-writing, Chinese characters are no longer ideographs capable of representing ideas directly; their comprehension relies on the reader's knowledge of the particular language being written. The areas where Chinese characters were historically used—sometimes collectively termed the
Sinosphere—have a long tradition of
lexicography attempting to explain and refine their use; for most of history, analysis revolved around a model first popularized in the 2nd-century
Shuowen Jiezi dictionary. More recent models have analysed the methods used to create characters, how characters are structured, and how they function in a given writing system.
Structural analysis Most characters can be analysed structurally as
compounds made of smaller
components (), which are often independent characters in their own right, adjusted to occupy a given position in the compound. Components within a character may serve a specific function:
phonetic components provide a hint for the character's pronunciation, and
semantic components indicate some element of the character's meaning. Components that serve neither function may be classified as pure
signs with no particular meaning, other than their presence distinguishing one character from another. A straightforward structural classification scheme may consist of three pure classes of
semantographs,
phonographs and
signs—having only semantic, phonetic, and form components respectively, as well as classes corresponding to each combination of component types. Of the characters that are frequently used in Standard Chinese, pure semantographs are estimated to be the rarest, accounting for about 5% of the lexicon, followed by pure signs with 18%, and semantic–form and phonetic–form compounds together accounting for 19%. The remaining 58% are phono-semantic compounds. The Chinese palaeographer
Qiu Xigui () presents three principles of character function adapted from earlier proposals by (1901–1979) and
Chen Mengjia (1911–1966), with
semantographs describing all characters whose forms are wholly related to their meaning, regardless of the method by which the meaning was originally depicted,
phonographs that include a phonetic component, and
loangraphs encompassing existing characters that have been borrowed to write other words. Qiu also acknowledges the existence of character classes that fall outside of these principles, such as pure signs. == Semantographs ==