A character is an abstract, atomic unit of communication. For example, the letter Q is a character in English.

Characters and glyphs are distinct concepts. A glyph is a particular image that represents a character or part of a character. Many glyphs may be used to denote the same character; for example, QQQQQ. Although recognizably different, these glyphs all represent the same abstract character Q. Similarly, some characters are represented by different glyphs depending on context, such as whether they occur in isolated, initial, medial, or final position.