Horizontal video scanning system that separates each video frame into two video fields, each of which is imaged at a distinct time. The contents of field 1 make up the odd-numbered lines (1, 3, 5,. . .) and those of field 2 make up the even-numbered lines (2, 4, 6,. . .) of the displayed video image. Interlaced scanning is used in both PAL and NTSC standard-definition broadcast video signals. Contrast with Progressive.