Great Vs. Shallow Depth Of Field

Great Depth Of Field: In the two photos on the
right the photographer's used a high f-stop
(aperture) in order to have evrything in frame, in
focus and sharp. This is usually used when taking landscape photos.

Shallow Depth Of Field: In the two photos on the left the photographer's used a low f-stop (aperture) to only have what they want to have in focus, and everything else in front or behind the subject of matter is blurred out to make the subject stand out.