If you've seen Lord of the Rings, or read any other fantasy story in which orcs are portrayed, you probably think orcs are hideous humanoid monsters charging mindlessly forward to slaughter helpless innocents. Azerothian orcs are significantly different, however, with a shamanistic culture that prides honor above all other virtues.
But unless you've played World of Warcraft or Warcraft 3, you probably wouldn't know that. The orcs of Warcraft 1 and 2 were pretty squarely in "bad guy" territory, and it is only with the story of Thrall's rise to power and return to shamanism that we find out what the orcs' true history is.
Ironically, the story of the orcs is a bit like that of the horrors of modern Nazis and the lore of the ancient Jews mixed together. Imagine that the vast majority of your species came under the sway of a terrible and evil leader, utterly determined to commit genocide against your peaceful neighbors. After carrying out this deplorable task, your people sought a new enemy, and found a new world to destroy. In the midst of this conquest, however, your people's political leadership failed, the way back home was cut off, and you all ended up as slaves in exile, lethargic and utterly without hope. Suddenly, a hero appeared to unite your people, overcome your former masters, restore your ancient faith, reclaim your dignity, and establish a new homeland.
What follows is a brief account of the events most orcs know about or lived through, and a glimpse of the effects they would have had on your character.