interlaced GIF
An interlaced GIF (Graphics Interchange Format) is a GIF image that seems to arrive on your display like an image coming through a slowly-opening Venetian blind. A fuzzy outline of an image is gradually replaced by seven successive waves of bit streams that fill in the missing lines until the image arrives at its full resolution. Among the advantages for the viewer using 14.4 Kbps and 28.8 Kbps modems are that the wait time for an image seems less and the viewer can sometimes get enough information about the image to decide to click on it or move elsewhere. For users with faster connections, there is little difference in effect between an interlaced GIF and a non-interlaced GIF.