GIF and JPEG
Most current browsers support graphics in either the GIF or JPEG format. Some older browsers may only support
GIF. GIF is CompuServe's Graphic Interchange Format for compressing images; it is the most common graphic file format
found on the Web, partially because it came first. JPEG (pronounced "JAY-peg") stands for Joint Photographic Experts Group,
the committee that established the standard.
When to use GIF
GIF is good for solid flat colors, sharp edges, for text and line art.
When to use JPEG
JPEG is good for photos; especially those with subtle gradations of color. JPEG will compress to a smaller file
size in these cases. JPEGs use 24-bit color so they can dither badly on 8-bit color monitors.