From the original Blizzard Entertainment game: In the Age of Chaos, two factions battled for dominance. The Kingdom of Azeroth was a prosperous one. The Humans who dwelled there turned the land into a paradise. The Knights of Stormwind, and the Clerics of Northshire Abbey, roamed far and wide serving the king's people with honor and justice. The well-trained armies of the King maintained a lasting peace for many generations. Then came the Orcish Hordes. No one knew where these creatures came from, and none were prepared for the terror that they spawned. Their warriors wielded axe and spear with deadly proficiency, while others rode Darkwolves as black as the moonless night. Unimagined were the destructive powers of their evil magiks, derived from the fires of the underworld. With an ingenious arsenal of weaponry and powerful magic, these two forces collide in a contest of cunning, intellect, and brute strength, with the victor claiming dominance over the whole of Azeroth.
Examples of the latest version.