High Dynamic Range Photography
High Dynamic Range or HDR photography is a method of composing images where one shoots multiple exposures (it is highly recommended that you use a tripod) of the same scene to capture details in the shadows, the mid-range and the highlights. Once you have the base images you use software such as Adobe Photoshop or Photomatix to combine the multiple exposures and create one single image.
For a quick and concise explanation, check out this YouTube video by Michael Eric Brown for a very good explanation of HDR photography.