An interlaced GIF is something different.
In a CRT display, there are several hundred horizontal lines in a frame (full screen). These lines are scanned from left to right, and from top to bottom. The refresh rate (number of frames scanned per second) varies, but it is normally between 60 and 100 hertz . Refresh rates slower than 60 Hz produce distracting screen flicker, which can cause headaches and eye fatigue.
Most CRT computer monitors scan each line in turn from top to bottom at the lowest resolution levels (640 x 480 and 800 x 600 pixel s). However, at the higher resolutions, such as 1024 x 768 or 1200 x 800, the frame is sometimes scanned in interlaced fashion: first the odd-numbered lines, and then the even-numbered lines. This allows for a lower refresh rate without producing flicker. With text and fixed graphics displays, this scheme can work well. However, with animated graphics -- especially images that move or change form rapidly -- interlacing can produce a fluttering effect at least as irritating as screen flicker.
For serious animated-graphics work and video editing, a non-interlaced display is recommended. The refresh rate should be as high as the system will allow, ideally 70 Hz or more.