When used in World of Warcraft, the term AH is an abbreviation for “auction house”. The auction house is a means of buying, auctioning and selling items in the game for gold. You can access the auction house by talking to an auctioneer in any racial major city in Kalimdor or Eastern Kingdoms. You can also use the auction house if you are an engineer by talking to the auctioneer robot located in the engineering shop in Dalaran, or by using Jeeves, a special engineering pet. The AH WoW term definition is very common, so expect virtually all other players to know what it means.