In typography, a ligature is a single glyph created from the combination of two or more characters. Ligatures are used to improve the appearance of certain letter combinations, often by joining them in a visually appealing way.
Ligatures are commonly used in fonts to replace specific character combinations that may clash or overlap when displayed. For example, the combination of lowercase “f” and “i” in many fonts is replaced by a ligature to avoid the awkward overlap of the dot of the “i” with the top of the “f.”