A friend has designed a graphic containing several words. Why should he/she choose to save this image file as a GIF rather than a JPG?
JPG's render true color poorly at some screen resolutions, whereas GIFs do not.
The GIF file format is tailored to the Internet, whereas the JPG was developed for storage only.
The file compression features of the JPG format may render the fonts unreadable.
JPG's are about three times the size of GIFs and therefore take more time to render in a browser.