Depth of field refers to the range of distance that appears sharp or the distance you can see for. It varies on camera and type of lens, aperture and focus distance. Depth of field has a smooth transition from sharp to blur and the focus distance begins to vanish.
Depth of field is can vary to different F stops from an DOF f/2.8 up to an f/30. Usually the higher the F stop the sharper the photo, the lower the F stop the blurrier the photo. Longer focal lengths may also appear to have a shallower depth of field because they enlarge the background relative to the foreground (due to their narrower angle of view).
shallow depth of field
A shallow depth of field is typically an F stop from f/2.8 and up to a maximum of f/7. If a picture has a 'shallow depth of field' typically that means then object in front is in focus, while the background is out of focus and gives it a 'blurred effect.'
deep depth of field
A deep depth of field is typically f/18 to a maximum of f/30. When a photo has a deep depth of field, the background and the object is usually in focus , allowing the viewer to see both the background and the object in clear detail. It has no 'blurred effect.'