A prune is simply a dried plum. Most of the plums that are grown for drying are European type plums, which have ‘freestone’ type pits. This simply means they have pits which are easy to remove.

Clingstone type plums are not suitable for drying; as the name implies, the stones are difficult to remove.

Prunes contain both sorbitol and a natural laxative compound called diphenyl isatin.