So you know, what "bracketing" means in general... taking a series of shots other than the one you or the meter have chosen.

Exposure bracketing is the most common. Right. It is done by the photographer or automatically by the camera, by taking an exposure at the suggested speed, aperture and ISO settings, and then one or more exposures using a different speed, aperture or ISO setting -- but always only one of these.

DoF bracketing is less common because DoF can be considered part of the composition and is a matter of artistic interpretation, something better left to the photographer rather than the camera. Like exposure bracketing, it can be done by the photographer or the camera (assuming your camera has DoF bracketing). But DoF bracketing is done by taking one exposure at the suggested speed, aperture and ISO settings, and then one or more exposures using a different aperture *and* a complimentary change in speed or ISO setting to compensate for the change in aperture. So, two settings are changed not just one.

If you can't think of a reason to use DoF bracketing, try to come up for a reason to use either speed or ISO bracketing in general use.

**In the case of Canon cameras**, however, there was once a function called DoF bracketing that allowed the photographer to focus on the nearest point they wanted in focus, take a reading by partially depressing the trigger, and then a second reading at the furthest point they wanted in focus and taking a second reading. This locked in that focus range by setting the aperture automatically and allowed the photographer to the photographer or program mode to modify the other two settings as needed to keep the focus. I haven't owned a Canon or worked at a camera shop since Moses so I'm not sure if Canon still uses that terminology.