The display of a video frame as two successive fields, each containing half the picture information. This system arose from limitation of early video display units. Each field is scanned onto the CRT from top to bottom, in a series of horizontal lines, (scanned left to right). The frequency at which these lines are scanned is reduced by a factor of 2 through the use of interlacing, thus lowering the design demands on the drive electronics. Contrast: progressivescanning