Depth of feild

F-stop
Aperture
Focal length
Focus
DOF (Depth of Feild)

DOF depends on-
Aperture Size (f-stop) (fraction of the size of lens, the smaller the number, the wider the hole, the wider the hole, the shallower the depth of feild or the less things are in focus)
Focal length
Distance of subject

Shallow depth of feild- one particular thing in focus, other things involved but less important out of focus

Deep depth of feild- most things in focus, sharp image