.GIF File Format

GIF has used widely on Internet for its wide support since introduced in 1987. It's one kind of bitmap image format that may contain up to 256 indexed colors. It also supports animations, in which only 256 colors at most are available for each frame. The color limitations makes the GIF format unsuitable for reproducing color photographs, but it is good for images with uncontinuous color, such as logos.

GIF files compress data with lossless compression method called Lempel-Ziv-Welch (LZW). Thus, they are more suitable to display small images and images that contain text and navigation symbol.

Different from GIF, JPEG (.JPG) images are better to present photos because there are generally no limit in the number of colors. GIF can include transparent pixels, which make it possible for GIF to work with different backgrounds. However, GIF image must be either fully transparent or fully opaque, so that the GIF is not as good as PNG format to be used as transparent images.

GIF images can comprises several images or frames to be displayed successively, which are often used to show simple animations on websites.