Bracketing

A little bit of HDR (High Dynamic Range) photography. The basic theory is to take multiple shots of the same subject, each time changing the exposure value by several stops. Then by using software, combine all three images and get a much wider tonal range than possible with one shot.

That's the theory anyway, sometimes it works (as here) other times the results are horrendous, just Google "HDR" for images of the abuse of this concept.