Uses for GIF and JPEG Files: Microsoft Internet Explorer, Netscape Navigator and most the other browsers maintain both JPEG and GIF graphics.
Theoretically, you could utilize either graphic format for the visual components of your Web pages. In practice, though, most Web developers still favour the GIF for main page design parts, diagrams and images that should not dither on 8-bit display screens.
Designers decide the JPEG format mostly for photographs and complicated "photographic" illustrations.