Marmalade is a fruit preserve made from the juice and peel of citrus fruits boiled with sugarand water. It can be produced from kumquats, lemons, limes, grapefruits, mandarins, sweet oranges, bergamots and other citrus fruits, or any combination thereof.
The benchmark citrus fruit for marmalade production in Britain is the Spanish Seville orange,Citrus aurantium var. aurantium, prized for its high pectin content, which gives a good set. The peel has a distinctive bitter taste which it imparts to the marmalade.
Marmalade is generally distinguished from jam by its fruit peel. It may also be distinguished from jam by the fruits used. (source:wikipedia)