Grapheme

In linguistics, a grapheme is the smallest unit of a writing system of any given language. An individual grapheme may or may not carry meaning by itself, and may or may not correspond to a single phoneme of the spoken language. Graphemes include alphabetic letters, typographic ligatures, Chinese characters, numerical digits, punctuation marks, and other individual symbols.

The word grapheme, coined in analogy with phoneme, is derived from Greek γράφω (gráphō), meaning "write", and the suffix -eme, by analogy with phoneme and other names of emic units. The study of graphemes is called graphemics.

The concept of graphemes is an abstract one and similar to the notion in computing of a character. By comparison, a specific shape that represents any particular grapheme in a specific typeface is called a glyph. For example, the grapheme corresponding to the abstract concept of "the Arabic numeral one" has two distinct glyphs (allographs) in the fonts Times New Roman and Helvetica.

Graphemes are often notated within angle brackets, as ⟨a⟩, ⟨B⟩, etc. This is analogous to the slash notation (/a/, /b/) used for phonemes, and the square bracket notation used for phonetic transcriptions ([a], [b]).

In the same way that the surface forms of phonemes are speech sounds or phones (and different phones representing the same phoneme are called allophones), the surface forms of graphemes are glyphs (sometimes "graphs"), namely concrete written representations of symbols, and different glyphs representing the same grapheme are called allographs. Hence a grapheme can be regarded as an abstraction of a collection of glyphs that are all semantically equivalent.

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