Letter spacing

Letter spacing, also called typographic tracking, adjusts spacing within a run of text. It is distinct from word spacing and from context-sensitive kerning. In CSS, the letter-spacing property controls additional spacing, with rules that respect the writing system rather than blindly separating every stored character.^[ref][ref]

A simple model illustrates the geometry. Suppose four already shaped units have combined advance $A=30$, and three selected internal gaps each receive an extra $t=0.5$. ThenThis is an explicitly chosen three-gap model. A glyph need not correspond to one stored character, so counting source characters is generally insufficient to determine those gaps. Text shaping, typographic ligatures and the script's joining behaviour must be considered when deciding where spacing may change.