A miniature is a small illustration used to decorate an ancient or medieval illuminated manuscript; the simple illustrations of the early codices having been miniated or delineated with that pigment. The generally small scale of such medieval pictures has led to etymological confusion with minuteness and to its application to small paintings, especially portrait miniatures, which did however grow from the same tradition and at least initially used similar techniques.

A portrait miniature is a miniature portrait painting, usually executed in gouache, watercolor, or enamel. Portrait miniatures developed out of the techniques of the miniatures in illuminated manuscripts, and were popular among 16th-century elites, mainly in England and France, and spread across the rest of Europe from the middle of the 18th century, remaining highly popular until the development of daguerreotypes and photography in the mid-19th century. They were usually intimate gifts given within the family, or by hopeful males in courtship, but some rulers, such as James I of England, gave large numbers as diplomatic or political gifts. They were especially likely to be painted when a family member was going to be absent for significant periods, whether a husband or son going to war or emigrating, or a daughter getting married.