The terms ‘glyph’ and ‘character’ are often mixed up, but there is a linguistic difference between them: a glyph is a specific representation of a character. For example, the character A can be represented by both glyphs A and a.

In digital typography, a glyph may be encoded or not. If it represents a distinct character, it will be assigned a Unicode code point. If it is a localized, positional or stylistic variant, it won’t have its own code point and is instead accessed via OpenType feature substitutions.

FONT ENGINEERING ADVICE

In a font file, the cmap table maps characters (code points) to glyph indices. The GSUB table defines all available glyph substitutions, enabling access to stylistic alternates, ligatures, and localized forms.