Further information: Greyhawk
The first published setting for D&D, created by D&D co-creator Gary Gygax. Greyhawk is Gygax's original campaign, expanded into an official game supplement and greatly expanded upon with many supplements. It is a "standard" medieval fantasy setting, similar in many ways to the Forgotten Realms campaign, but overall darker in tone, with a sword and sorcery feel. Greyhawk is the "default" setting for the 3rd Edition ruleset (that is, the rulebooks are written assuming the players are campaigning in the Greyhawk setting) but supplements are no longer actively published. This campaign setting is no longer officially supported.
Read more about this topic: Dungeons & Dragons Campaign Settings