User summary (details from Wikipedia):
World of Warcraft: The Burning Crusade is the first expansion pack for the MMORPG World of Warcraft. It was released on January 16, 2007 at midnight (12:00 AM) in Europe and North America, and sold nearly 2.4 million copies that day to people who waited over night in the to get the expansion, making it the fastest-selling PC game in those regions.
This expansion adds two new races: The Blood Elves for the Horde and the Draenei for the Alliance. It also adds the new continent of Outlands, and the ability to level up to level 70.
Source: Wikipedia, "Burning_Crusade," available under the CC-BY-SA License.