Noun
a written symbol that is used to represent speech
Source: WordNetthe Greek alphabet has 24 characters Source: Internet
A phoneme may be represented by a multigraph (sequence of more than one grapheme), as the digraph sh represents a single sound in English (and sometimes a single grapheme may represent more than one phoneme, as with the Russian letter я ). Source: Internet
Coulmas, F. (1996), The Blackwell's Encyclopedia of Writing Systems, Oxford: Blackwells, p.174 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. Source: Internet
In Spanish and several other world languages influenced by it, the grapheme ñ represents a palatal nasal consonant. Source: Internet
Each grapheme may represent a limited number of phonemes depending on etymology and location in the word. Source: Internet
For example, different forms of the letter "b" are all considered to represent a single grapheme in the orthography of, say, English. Source: Internet