It is known that data, once entered, are organized and stored in successively more comprehensive groupings. Generally, these groupings are called a data storage hierarchy. The general groupings of any data storage hierarchy are as follows.
1) Characters, which are all written language symbols: letters, numbers, and special symbols. 2) Data elements, which are meaningful collections of related characters. Data elements are also called data items or fields. 3) Records, which are collections of related data elements. 4) Files, which are collections of related records. A set of related files is called a data base or a data bank.