Forgotten Realms is byfar the most popular and detailed campaign world in all of AD&D. In this world, gods walk the Earth, and armies often clash.
This is the home of Elminster the sage and Drizzt the dark elf-two heros featured in the Forgotten Realms novel line.
Forgotten Realms, the Forgotten Realms logo, and AD&D are property of TSR, Inc.