Interlaced scanning is a method for processing video signals by separating a video frame to two fields which were assigned alternating scan lines.

A interlaced signal has twice the frame-rate but half the resolution of progressive signal. To process a 25 frames per second movie in interlaced mode, each frame is split into 2 fields, one contains the odd number lines (1,3,5...), the other contains the even number lines(2,4,6...). And the signals are send at the rate of 50 fields per seconds.

Interlaced scanning method is widely used in today's HDTV as well as analog TV. Interlaced method is abbreviated as "i" in DTV format. The other scanning method is called Progressive.