A prune is any of various plum species, mostly Prunus domestica or European Plum. It is called 'Alu-bukhara' in Iran, India, Pakistan and Bangladesh. They are usually sold as dried fruit. The dried fruit (also referred to as a dried plum) is wrinkly in texture, and has chewy flesh. Fresh plums that are marketed as "prunes" have an oval shape and a more easily removed pit.

More than 1,000 cultivars of plums are grown for drying. The main cultivar grown in the US is the Improved French prune. Other varieties include Sutter, Tulare Giant, Moyer, Imperial, Italian, and Greengage. In general, fresh prunes are freestone cultivars (the pit is easy to remove), whereas most other plums grown for fresh consumption are cling (the pit is more difficult to remove). Fresh prunes reach the market earlier than fresh plums and are usually smaller in size.

Due to popular perception of prunes being used for constipation in older people, and being the subject of related distasteful joking, many of today's distributors have stopped using the word on the package label. Their preference is to state "dried plums".

Prunes are used in cooking both sweet and savory dishes. Stewed prunes, a compote, are a dessert. Prunes are a frequent ingredient in North African tagines. Perhaps the best-known gastronomic prunes are those of Agen (pruneaux d'Agen). Prunes are used frequently in Tzimmes, a traditional Jewish dish in which the principal ingredient is diced or sliced carrots; and in the traditional Norwegian desserts fruktsuppe and sviskekompott. Prunes have also been included in other holiday dishes, such as stuffing, cake, and to make sugar plums.

Prune juice is made by softening prunes through steaming and then putting them through a pulper to create a watery puree. Prunes and their "juice" contain the natural laxative dihydrophenylisatin (related to isatin). Faster results are obtained by heating the prune juice. Prunes also contain dietary fiber (about 6%, or 0.06 g per gram of prune). Prunes and prune juice are thus common home remedies for constipation. Prunes also have a high antioxidant content. In China, the popular summer drink suanmeitang, made with sour prunes, is sometimes thought to have positive effects on acidity in the body.