Glossary » interlacing
displaying images by drawing only a partial image first, consisting of alternate lines, or every 3rd or 4th line, then filling in the remaining lines progressively. When images are displayed slowly, such as large gifs slowly downloading off the internet, this permits a useful preview of the image as it arrives. Interlacing is also used in the NTSC broadcast television standard to give the impression of a faster screen refresh rate — every 60th of a second, alternate lines (even or odd) are updated on the screen. Thus, the full screen is updated only every 30th of a second, but the impression is of faster refresh.