Chinese characters are logographs used to write the Chinese languages and others from regions historically influenced by Chinese culture. Of the four independently invented writing systems accepted by scholars, they represent the only one that has remained in continuous use. Over a documented history spanning more than three millennia, the function, style, and means of writing characters have changed greatly. Unlike letters in alphabets that reflect the sounds of speech, Chinese characters generally represent morphemes, the units of meaning in a language. Writing all of the frequently used vocabulary in a language requires roughly 2000–3000 characters; as of 2025^[update], more than 100000 have been identified and included in The Unicode Standard. Characters are created according to several principles, where aspects of shape and pronunciation may be used to indicate the character's meaning.

The first attested characters are oracle bone inscriptions made during the 13th century BCE in what is now Anyang, Henan, as part of divinations conducted by the Shang dynasty royal house. Character forms were originally ideographic or pictographic in style, but evolved as writing spread across China. Numerous attempts have been made to reform the script, including the promotion of small seal script by the Qin dynasty (221–206 BCE). Clerical script, which had matured by the early Han dynasty (202 BCE – 220 CE), abstracted the forms of characters—obscuring their pictographic origins in favour of making them easier to write. Following the Han, regular script emerged as the result of cursive influence on clerical script, and has been the primary style used for characters since. Informed by a long tradition of lexicography, states using Chinese characters have standardized their forms—broadly, simplified characters are used to write Chinese in mainland China, Singapore, and Malaysia, while traditional characters are used in Taiwan, Hong Kong, and Macau.

Where the use of characters spread beyond China, they were initially used to write Literary Chinese; they were then often adapted to write local languages spoken throughout the Sinosphere. In Japanese, Korean, and Vietnamese, Chinese characters are known as kanji, hanja, and chữ Hán respectively. Writing traditions also emerged for some of the other languages of China, like the sawndip script used to write the Zhuang languages of Guangxi. Each of these written vernaculars used existing characters to write the language's native vocabulary, as well as the loanwords it borrowed from Chinese. In addition, each invented characters for local use. In written Korean and Vietnamese, Chinese characters have largely been replaced with alphabets—leaving Japanese as the only major non-Chinese language still written using them, alongside the other elements of the Japanese writing system.

At the most basic level, characters are composed of strokes that are written in a fixed order. Historically, methods of writing characters have included inscribing stone, bone, or bronze; brushing ink onto silk, bamboo, or paper; and printing with woodblocks or moveable type. Technologies invented since the 19th century to facilitate the use of characters include telegraph codes and typewriters, as well as input methods and text encodings on computers.

Chinese characters are accepted as representing one of four independent inventions of writing in human history. In each instance, writing evolved from a system using two distinct types of ideographs—either pictographs visually depicting objects or concepts, or fixed signs representing concepts only by shared convention. These systems are classified as proto-writing, because the techniques they used were insufficient to carry the meaning of spoken language by themselves.

Various innovations were required for Chinese characters to emerge from proto-writing. Firstly, pictographs became distinct from simple pictures in use and appearance—for example, the pictograph 大, meaning 'large', was originally a picture of a large man, but one would need to be aware of its specific meaning in order to interpret the sequence 大鹿 as signifying 'large deer', rather than being a picture of a large man and a deer next to one another. Due to this process of abstraction, as well as to make characters easier to write, pictographs gradually became more simplified and regularized—often to the extent that the original objects represented are no longer obvious.

This proto-writing system was limited to representing a relatively narrow range of ideas with a comparatively small library of symbols. This compelled innovations that allowed for symbols which indicated elements of spoken language directly. In each historical case, this was accomplished by some form of the rebus technique, where the symbol for a word is used to indicate a different word with a similar pronunciation, depending on context. This allowed for words that lacked a plausible pictographic representation to be written down for the first time. This technique preempted more sophisticated methods of character creation that would further expand the lexicon. The process whereby writing emerged from proto-writing took place over a long period; when the purely pictorial use of symbols disappeared, leaving only those representing spoken words, the process was complete.

Chinese characters have been used in several different writing systems throughout history. A writing system is most commonly defined to include 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 a language's morphemes, its most basic units of meaning. 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 characterized 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.