Depth of field is the distance between the farthest and nearest focus area or it is simply the length of distance of the focus area in a photograph. A photograph can obtain a shallow or deep depth of field depending on the aperture, focal length and focus distance.
A photograph can be said to have a shallow depth of field if the picture has a small focus distance. The subject is in focus but the background is mostly or completely blurred or out of focus. Shallow depth of field will lead the viewer’s eyes to the focused subject or area. There are some fields in photography that shallow depth of field is often used like in portrait, glamour and food photography.