Of course bracketing can be applied with a manual exposure setting, but the light meter has to be set by the photographer for each frame.

Many modern professional SLR cameras, both film and digital have a button that allows for exposure bracketing. This is where the camera is programmed to take several shots of the same subject but alter the exposure between each shot. For instance, in either Aperture priority, shutter priority or program (all of which are auto exposure setting), the program might allow for a range of shots to be taken on different exposure settings up to 2stops over and 2 stops under exposure in 1/2 stop variations.

So if the aperture priority setting was used and the read exposure was an aperture of f8 @ a shutter speed of 1/125 sec - the bracketing was set to under expose for 2 stops, the camera would take the following shots adjusting the exposure for each shot.

Normal - f8 @ 1/125 sec

1/2 stop under - f8 @ 1/90 sec

1 stop under - f8 @ 1/60 sec

11/2 stops under - f8 @ 1/45 sec

2 stops under - f8 @ 1/30 sec

Remember because the camera is set on Aperture Priority or AV the aperture remains the same.