Many modern DSLR and some high end point-and-shoot camera’s have a Bracketing option. This instructs the camera to take a series of shots at different exposures. Usually three shots are taken, one using the current settings, the second 1 f-stop below and the third, 1 f-stop above.
Depending on your camera you may need three presses of the shutter release to capture the three shots. However some provide an automatic option where one press will take the three differently exposed shots one after the other.
Bracketing is useful in difficult lighting conditions were contrast can be difficult. By taking the shot with three different exposures the best can be chosen later on. Because the camera cannot take three shots simultaneously Bracketing doesn’t work for fast action shots. However this all depends on the ‘drive’ speed of your camera.
Cameras allow the Bracketing width to be adjusted. For RAW images one stop is usually acceptable. However if shooting JPEG’s it’s a good idea to make the gap closer as there is less opportunity to adjust later on.