Carbohydrates are a family of naturally occurring substances of varying sweetness comprising hydrogen, carbon and oxygen. Sugars, starches and celluloses are sub-sections of the family but in this chapter the focus is on sugars and in particular on sucrose, the most important member of the family. Sucrose, or sugar as it is commonly known, occurs widely in nature. It is present in the juice of most fruit and some root vegetables notably the sugar beet Beta vulgaris which is a temperate climatic zone plant. It occurs in the sap of many trees such as the American sugar maple Acer saccharum, the carob Ceratonia siliqua, and certain palm trees. It is also found in the stem and roots of grasses, particularly the sub-tropical continental grass, the sugar cane Saccharum officinarum.