1) Depth of field is, When a spicific portion of a scene in the picture is shapper then the rest of the image.
2) The difference between large and small depth of field is that, Small depth of field is when a small focal point is sharp, and then when theirs a bigger focal point that image would be shepper also.
3) My photo shows depth of field because, in the 1st photo, the camera is in focus and the person is not. The 2nd picture, the railing is in focus, and the background railing is not, and in the rd picture the railing is in focus, and the stairs/window isnt infocus.