The D.C. Universe is the setting for all of the D.C. hero's stories. Batman, Superman, and The Flash are just a few of the superheros whom called this realm home. The concept of a universe with all the hero's interacting with each other was actually pioneered by the D.C. Comics with writer Gardner Fox spearheading the way. The hero's where all apart of the basic concept of being alive in the real world. Yet, Earth in this series is slightly bigger than real life and has main cities and even whole countries totally destroyed. All in all though the history is pretty much the same in real life. When it comes to the superhumans and their strengths, it is mostly due to "metagene". A genetic feature of unknown origin that causes superpowers when exposed to dangerous substances and forces. Some owe their powers to magic, mutation, or bionics. Yet still others owe their powers to just plain training and technology, such story is that of Batman.