Bracketing is taking multiple photos of the same scene, but with the light exposure settings changed in each photo so that the primary light exposure is bracketed with darker exposure and a lighter exposure. Many digital cameras have a bracketing setting.
With bracketing, if the camera doesn't read the lighting properly, one of the bracketed photos will likely give a better picture.
Bracketing also helps in situations where there is extreme bright and dark contrast in a photo.The tonal range of a camera sensor is not as great as that of the human eye. In some high contrast situations a mid-range setting (what the camera usually selects) will result in a photo in which all of the bright tones are blown out to pure white, while many dark tones are rendered as complete black. You see this often in landscape photos with bright clouds in the sky and shadows in the landforms. Pictures of snowy mountains often suffer this way as well. With bracketed exposures and a robust photo processing program, you can create an image that captures the tonal range by combining appropriate elements from the bracketed exposures. Here is a
Corel tutorial on High Dynamic Range (HDR), as this process is known.
The picture of Davis Bay beach above is an example of a high contrast setting. The shadows in the foreground are very dark, but if I used a brighter exposure the light on the water in the left side of the photo would blow out to pure white and the glints of the wavetops would disappear. In making that photo I cropped the photo to remove a more of the brightly illuminated water on the left side of the photo. In the exposure that I used for the photo some of that water area was blown out to ure white. I had a bracketed exposure with a lower setting in which the detail remained in the water, but then the shadow area in the foreground were even more intense. I selected the exposure and cropped the photo as I did primarily because I liked the composition of the cropped photo more than the original, but the reduced dynamic range of the photo after cropping was also a consideration. I still left some deep shadows in the foreground. I could have selectively lightened those areas, but when I opened those areas up I thought I lost some of the moodiness of the photo.