GIF vs. JPEG:
A gif is used when you only want the 256 web safe colors. It is most useful when you want something to keep its sharpness. Examples of when you use a gif would be a banner or a button. A gif is compressed to a tenth of its original size. One would want to use a JPEG for Photographs because it keeps all of its colors. The downside to a JPEG is that it loses some of its sharpness. A mathematical formula is used to shrink it down.