ligatures

A ligature is a typographic or handwriting unit in which two or more letterforms are combined into a single glyph. Ligatures arise from the practical needs of writing and typesetting, often to improve readability, reduce spatial clashes, or create a more harmonious appearance. They are most commonly associated with Latin-script alphabets, but ligatures can occur in other writing systems as well.

Historically, ligatures appeared in medieval manuscripts as scribes linked letters with shared strokes. The practice carried into early printing, where metal type constrained the spacing of characters. In many traditional typefaces, common combinations such as fi, fl, and the rarer ffi and ffl were set as ligatures to prevent collisions with ascenders and to save space. Other well-known examples include æ (a e) and œ (o e). Some early type was even designed around the idea of a long s ligature, a feature now largely obsolete. Modern fonts continue to include ligatures for aesthetic and legibility reasons, and many historically significant ligatures persist in blackletter and serif faces.

In digital typography, ligatures are typically implemented as OpenType features. The standard set, often labeled liga, can be enabled or disabled by the user or the layout engine. Designers may choose discretionary ligatures for style, or rely on context-based ligatures that substitute appropriate forms automatically at small sizes. Ligatures remain a common tool for balancing typographic texture and readability.