Glossary of Web Terms
Probably the most common format for images on the web. JPEGs are best suited for photos and images of that nature. JPEG stands for Joint Photographic Experts Group, which is the committee that came up with the whole thing to begin with. Its a good thing, and we have those folks to thank.
For comparison, the first image below was exported as a JPEG. The second photo was exported as a GIF. The differences between the two are easy to see.