A raisin is a dried grape used as a method of preserving the fruit, similar to the concept of prunes. Raisins are generally dark purple (from purple grapes) or beige (from white grapes). They are containing the matter of the grape skin, and are wrinkled from the relatively smaller space left by the water taken out during drying. They are generally very sweet from their highly crystallized sugar content. They are also often featured in products such as fruit cake and trail mix.