High Dynamic and Extended Dynamic range photos are created by combining the exposure data from anywhere from 3-7 photos exposed from +/- 3 stops from an averaged exposure.

As good as modern cameras are, they still can't cover the unlimited amount of dynamic range that the human eye can resolve. Dynamic range being the ability to not only see details in shadows, but also highlighted (read: bright) areas simultaneously. Despite that, photographic techniques and hardware changes are quickly pushing these types of photos as the standard.

High Dynamic Range photos take Extended Dynamic photos one step further, resolving detail that even the human eye is incapable of processing at a glance. Those photos have a prefix of HDR.