A subdivision of a database record in which a specific type of data is entered.

Using the analogy of a card catalog in a public library: if the card catalog is directly analagous to a database, and if the cards in the catalog are directly analagous to database records, then the different subdivisions of information found in each card in the catalog (title, author, publishing date, etc.) are all database fields.

Database fields are functionally equivalent to markup language elements.