Also note that power leveling is sometimes used to refer to paying someone else to level your character to cap as fast as possible (i.e. they power level for you); a distinction used by Blizzard is to refer to the paid leveling as "power leveling service." This behavior is against Blizzard's Terms of Service. Power leveling yourself, which this article covers, is perfectly acceptable.
Let's face it, World of Warcraft has an awful lot of content available, especially when it comes to end game content. Unfortunately, that can quite time consuming and not everyone can afford to spend so much time getting there. Wouldn't it be great if there was a way to skip all the grueling and time-consuming leveling process and just jump right into the end game? Thankfully, there is - WoW leveling service!