For the record: an image with a lot of contrast and dark areas is not a HDR picture. The opposite is true, an HDR image shows details in all areas, with reduced contrast.
In photo: Several exposures can be combined into one, each exposed perfectly for certain parts of the photo, and themn merged so you see detail in sky (not overexposed) and shadow (usually dark).
Examples.
http://www.google.se/images?q=hdr&oe...w=1005&bih=648
Technique:
http://www.cambridgeincolour.com/tut...amic-range.htm
Please stop saying the bottom photo of the two submitted earlier has a HDR.