Hydra uses a number of regular photographs (up to four) with different exposures (darker and lighter) to create a superior one which is much closer to what one's eye can see. This is because a single photograph cannot represent the full gamut of light because of physical limitations in the sensor. This process is also known as a high dynamic range, or HDR, imaging. See the screencast tutorials for more information on how to acquire such images with your camera.
The output produced by Hydra is much closer to what your eye actually sees. You don't have to choose whether to have a beautiful sky or buildings, take 2 photos (or more) with perfect parameters for each of them, then combine them with Hydra.
The images that Hydra uses are not required to be taken with a tripod, as it is usually the case with HDR software. Hydra uses the same warping algorithm as Morph Age, which permits the alignment of images with offsets above a few pixels. This is a unique feature that means you can take photos anywhere without a tripod to later blend them in Hydra. This will change your way of making HDRs.