.jpeg or .jpg
(pronounced "j-peg") There are two names to denote this format because of the PC and MAC formats allowing
3 and 4 letters after the dot. JPEG is an acronym for Joint Photographic Experts Group, the organization
that invented the format.The format is unique in that it uses compression after it's been created.
That's fancy computer talk that means that when the computer is not using a .jpeg image it folds it up
and puts it away. For example, if the picture is 10K bytes when displayed, it may be only 4K bytes when
stored. Nice trick, huh? It saves on hard drive space, but also tends to require a bit of memory on your
part to unfold the image.Someone always writes to me to tell me that .gif images also use compression.
Yes, they do, but only when they are first created into that format. After that, no compression. JPEG,
on the other hand, uses compression throughout its life to fold up smaller than it really is.