Depth of Field (DOF) is the distance in front of and behind the subject which appears to be in focus. DOF is generally achieved thru photography. Camera lens only foucus a certain distance on a subject, and things in the photo that are not the same distance away tend to be "soft" or "blurry" unless you have your camera set to avoid it. Read [link] for an understanding on how a camera does it. Therre you will find good examples of photos with DOF and without.

Artificial Depth Of Field is done in a photo manipulation quite easily and can be used to add DOF to any photograph/image. In "Oil Worth [link] " and "Cold Barb [link] " the backgrounds were blurred to look out of focus, this shifts attention to the canon and the barbwire in my example images and also gives them more of a "photo" look. This can be done with none photos aswell. I've seen cartoon animations where the background had been softened to help give the image more "depth." It's a very simple technique that can turn a average image into something breathtaking.