They are useful because they often provide more complex and informed definitions than a general dictionary. Any collection of information that serves these purposes qualifies as a database, even if the information isn't stored on a computer. In fact, important predecessors of today's sophisticated business database systems were files kept on index cards and stored in file cabinets. A filing cabinet, then, filled with files is a non computerized database. Database records are defined by fields.
Fields are storage areas for particular kinds of data.
Let's look at a record from LSU's old card catalog . The subject field stores information about the book's subject. This information is collectively called a subject heading. You could also search for the book by author or title, two other searchable fields in a card catalog. On the left hand side of the car is its call number , PQ 6277 02.