Please note that the content of this book primarily consists of articles available from Wikipedia or other free sources online.In computer programming, an enumerated type (also called enumeration or enum) is a data type consisting of a set of named values called elements, members or enumerators of the type. The enumerator names are usually identifiers that behave as constants in the language. A variable that has been declared as having an enumerated type can be assigned any of the enumerators as a value. For example, the four suits in a deck of playing cards may be four enumerators named CLUB, DIAMOND, HEART, SPADE, belonging to an enumerated type named suits. If a variable V is declared having suits as its data type, one can assign any of those four values to it. The enumerators are necessarily distinct, even though some languages may allow the same enumerator to be listed twice in the type's declaration. The enumerators need not be complete or compatible in any sense. For example, an enumerated type called color may be defined to consist of the enumerators RED, GREEN, ZEBRA, and MISSING. In some languages, the declaration of an enumerated type also defines an ordering of its members.