Which expansion introduced flying mounts?

The Burning Crusade introduced flying mounts to World of Warcraft. When the expansion launched in January 2007, level-70 characters could learn to ride through the skies of Outland using specialized flying mounts.

This was a major change to exploration and travel because the original game’s characters were restricted to ground movement outside a few special transport systems. Flying made Outland’s enormous zones easier to cross and opened access to elevated areas, including locations involved in quests, gathering, and endgame content. The first flying system was initially limited to Outland rather than the original continents.

A common mix-up involves Wrath of the Lich King. That expansion expanded flying to Northrend and added the Cold Weather Flying skill, but it did not introduce the concept. Cataclysm later enabled flying across much of the redesigned Eastern Kingdoms and Kalimdor. The Burning Crusade also added the Draenei and Blood Elf races, raised the level cap from 60 to 70, and introduced the Outland setting.