GIF (Graphic Interchange Format)

A GIF (the original and preferred pronunciation is JIF) is one of the two most common file formats for graphic images on the World Wide Web. The other is the JPEG.

The GIF option restricts you to 256 colors. But don't write off the GIF just yet. For one thing, the JPEG format does not work well for graphics that contain large fields of color - these color fields can break up and fragment and look terrible.

Furthermore, an image's compression format shapes the way a browser can download it, and browsers can do several things with GIFs that JPEGs don't support. One of the advantages to a GIF is that you can interlace it. Interlaced GIFs appear first with poor resolution and then improve in resolution until the entire image has arrived, allowing the viewer to get a quick idea of what the picture will look like while waiting for the rest. JPEGs can only arrive linearly, from the top row to the bottom row.

Another plus is that the background of a GIF can be made transparent, so you see the background color of the browser window you're in.

Finally, GIFs can also be animated. Poor old JPEGs just have to stand still. There are two versions of the format, 87a and 89a. Version 89a (July, 1989) allows for the possibility of an animated GIF, which is a short sequence of images within a single GIF file. A GIF89a can also be specified for interlaced presentation.