Power leveling is the term used to describe the process of leveling a character as rapidly as possible with the least amount of play time. It can be used from any level up to the maximum level in the game which is currently 90. Contrary to what many believe, efficient power leveling does not require endless hours of grinding. The best methods of power leveling involve doing many quests in an orderly fashion.
The goal of these guides is to help you level a character, whether your first on the server or not, to the level of your choice as quickly and efficiently as possible. At the same the quests will be ordered in such fashion to ensure you gain reputation with each of the 3 major factions on either the Alliance or Horde side.
With regard to professions, an example would be for a tailor to farm or purchase large quantities of cloth, then identify and repeat the cheapest tailoring recipes so as to maximize skill point gain compared to cost.
Common methods of power leveling include doing only those quests which are most efficient in terms of experience over time, and analyzing the quests in a given zone so as to do them in the most efficient order possible. Remember, the idea of power leveling is speed and efficiency–you may wish to obtain an addon that will show you how much experience per hour you are gaining to test your techniques. Additionally, ensure your character’s talent build is crafted for maximum endurance. You want as little downtime (walking, drinking, eating, crafting, typing, etc.) as possible.
Twinking is distinct from power leveling. A twink is usually intended to remain at its current level for an extended period of time, thus providing some justification for the large investment into its gear. A character being power leveled is often equipped with inexpensive gear, since the player will be planning on outleveling it quickly.
Also note that power leveling is sometimes used to refer to paying someone else to level your character to 80 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.