Similar to Earth, Azeroth's surface consists mostly of water and its landmass is divided into four continents: the Eastern Kingdoms, Kalimdor, Northrend, and Pandaria. In between these continents lie the Maelstrom, an everlasting cyclone within a thunderstorm which is a rift between the physical plane and the elemental planes.
Map of Azeroth
Azeroth's creation and purpose is a mystery, but many assume it was created by a long lost race of god-like beings called the Titans.
Inhabitants: Humans, Dwarves, Gnomes, Night Elves, High Elves, Half Elves, Blood Elves, Orcs, Trolls, Tauren, Undead, Earthen, Vrykul, Pandaren, Centaur, Satyr, Naga, Dragons, Ancients, Elementals
Government(s): Hereditary monarchy, tribal chiefdom, confederal chiefdom
War of the Ancients
Azeroth's earliest recorded history date back to more or less 10,000 years prior to the events of the original Warcraft trilogy. At the time, the Night Elves built one of Azeroth's greatest empires upon the then-intact landmass of Kalimdor by using Arcane magic to conquer rival races. However, their queen Azshara and her court sorcerers, dubbed the Highborne, was tricked by Sargeras, the Dark Titan who plotted to destroy Azeroth and the rest of the universe, into summoning both his physical form and the Burning Legion into the mortal realm. Before he could fully manifest his form however, the brothers Malfurion and Illidan Stormrage along with priestess Tyrande Whisperwind, assemble and army of rebel Night Elves, the Earthen, the Tauren, and the Dragon Aspects tasked by the Titans to guard Azeroth in order to repel Sargeras' invasion force. The combatants succeed in repelling the demons, defeating Azshara, and finally destroying the portal from which Sargeras would emerge.
Their victory, however, was not without a cost. The portal's destruction exploded in a storm of untamed Arcane energies, sundering Kalimdor into the four continents which appear today.
The Night Elves who were not allied with Queen Azshara abhorred the practice of Arcane magic, forcing the rebellious Highborne who had assisted them to abandon their alliance, sailing east to the Eastern Kingdoms where they would evolve to become High Elves.
At some point during this age, the nocturnal Night Elves were granted immortality by the Dragon Aspects through the World Tree Nordrassil. In place of the Highborne monarchy, the Night Elves formed a druidic leadership where male Elves would safeguard the Emerald Dream while the female Elves would become warriors and priestesses acting as the Elven primary police and military force.
Aside from this, not much history is known about what happened during these 10,000 years.
The First War
After 10,000 years of waiting, Sargeras and his Legion again attempted the destruction of Azeroth, this time targeting the human monarchies in the Eastern Kingdoms.
Possessing the renowned Guardian of Tirisfal Medivh, Sargeras assassinated every known member of the Council of Tirisfal, an order of mages dedicated to protect the world from demonic threats. He then proceeded to commune with Gul'dan, a warlock from the corrupted Orcish world of Draenor, to build a portal which would unleash the Old Horde upon the human kingdom of Stormwind.
Unprepared for a war with demonic forces, Stormwind crumbled in a two-year war, ending with the King Llane Wrynn's assassination at the hands of half-orc agent Garona Halforcen. The victorious Horde forces defiled and plundered Stormwind while Sir Anduin Lothar and Crown Prince Varian Wrynn along with Stormwind's survivors fled to the neighboring kingdom of Lordaeron.
The Second War
After serious tension buildups between the Alliance of Lordaeron and the Old Horde, another war erupted, devastating many landscapes and consuming the lives of many. Similar to Draenor's Tanaan Jungle, the swampy region of Black Morass where the Azeroth side of the Dark Portal was located became a lifeless barren wasteland due to the Portal's demonic magic.
After the Kingdom of Alterac was obliterated by Alliance forces, the orcs of the Frostwolf Clan came to inhabit it.