The purpose of HDR photography is to create an image of a scene that has a greater range of light values than can be normally be captured by a single film or digital image. Depending on how it is used, HDR imaging software can allow the photographer to create an image that is closer to what the human eye perceives when looking at a high dynamic range scene.
However, more and more it is being used to create surreal, whimsical or fantastical photo illustrations that don’t necessarily reflect the human experience but fall into a whole new genre of photographic art
Most simply put, dynamic range, as it applies to photography, is the difference between the maximum (brightest) and minimum (darkest) measurable light intensities for a given scene, film, sensor, screen, etc. This range in photography is often referred to in terms of stops. A stop equals a doubling of the amount of light.