InDesign can automatically insert ligatures, which are typographic replacement characters for certain letter pairs, such as “fi” and “fl,” when they are available in a given font. The characters that InDesign uses when the Ligature option is selected appear and print as ligatures, but are fully editable, and do not cause the spell checker to flag a word erroneously.

With OpenType fonts, when you choose Ligatures from the Character panel menu or Control panel menu, InDesign produces any standard ligature defined in the font, as determined by the font designer. However, some fonts include more ornate, optional ligatures, which can be produced when you choose the Discretionary Ligatures command.