In a database, one particular data element in a record, such as a street address in one record in a mailing-list database, for example. A fixed field only allows a certain number of characters to be used in the field, regardless of how much data a particular record contains, while a variable field is designated with start and end codes and thus can vary from record to record depending upon the amount of actual data in the field.
In television and video, a field is essentially one-half of a video picture. When a video signal is scanned onto a screen, first all the even-numbered horizontal lines are scanned from the top of the screen to the bottom, then all the odd-numbered lines are scanned. Each of these "halves" is known as a field. Two fields make up one frame.