Quest Add-Ons

• For your first character, it is much better to play without any quest-related add-ons. This way, you can experience the game as it was meant to be played, complete with numerous challenges and surprises. However, if you are leveling up a second, third or fourth character, the grind often starts to get a bit boring for most players. If this is the case, a quest add-on can speed up the leveling process and cut out those long amounts of time spent looking for a particular quest giver or location. Popular quest add-ons include QuestHelper, Carbonite Quest, LightHeaded and TourGuide.
  
  

Auction House Add-Ons

• The auction house is the most important part of the in-game economy, and the vast majority of most player's gold income comes from working the auction house. While the default auction house interface is adequate for most casual players, an auction house add-on can make it easier to list large quantities of items, review market trends and set prices. Popular auction house add-ons include Auctionator and Auction Profit Master.
  
  

Map Add-Ons

• Map add-ons help you to find certain destinations quicker. They are often closely related to questing add-ons, if not integrated with them. Popular add-ons such as Atlas and its components enhance the world map and provide further information on loot drops and rare monsters. Another popular add-on is TomTom, your own personal in-game GPS, pointing you to your desired destination with a big red arrow at the top of the screen. TomTom can be combined with questing add-ons such as TourGuide.
  
  

Spam Filters

• Although Blizzard provides a spam filter by default, it is not as efficient as third-party add-ons like BadBoy, which automatically blocks and reports incoming spam messages. It is an essential add-on if you want to block whispers and trade chat messages from dominating your gaming experience, especially on busy servers.
  
  

Damage Meters

• A damage meter is an add-on that shows how much overall damage and damage per second you and members in your party are doing. This is important for gauging the capabilities of characters in raids and dungeons. The most commonly used one is Recount.