Chinese character classification

Chinese characters are generally logographs, but can be further categorized based on the manner of their creation or derivation. Some characters may be analysed structurally as compounds created from smaller components, while some are not decomposable in this way. A small number of characters originate as pictographs and ideographs, but the vast majority are what are called phono-semantic compounds, which involve an element of pronunciation in their meaning.

A traditional six-fold classification scheme was originally popularized in the 2nd century CE, and remained the dominant lens for analysis for almost two millennia, but with the benefit of a greater body of historical evidence, recent scholarship has variously challenged and discarded those categories. In older literature, Chinese characters are often referred to as "ideographs", inheriting a historical misconception of Egyptian hieroglyphs.

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.

Most characters can be analysed structurally as compounds made of smaller components (部件; bùjiàn), 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 3500 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 (b. 1935) presents three principles of character function adapted from earlier proposals by Tang Lan [zh] (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.

Most of the oldest characters are pictographs (象形; xiàngxíng), representational pictures of physical objects. Examples include 日 ('Sun'), 月 ('Moon'), and 木 ('tree'). Over time, the forms of pictographs have been simplified in order to make them easier to write. As a result, it is often no longer evident what thing was originally being depicted by a pictograph; without knowing the context of its origin in picture-writing, it may be interpreted instead as a pure sign. However, if its use in compounds still reflects a pictograph's original meaning, as with 日 in 晴 ('clear sky'), it can still be analysed as a semantic component.