King, added a third continent, Northrend . to Azeroth, and in Mists of Pandaria a fourth continent, Pandaria, was added. In Legion, they introduce the Broken Isles. With the Battle for Azeroth expansion came 2 new continents, Kul Tiras (mainly for Alliance) and Zandalar (mainly for the Horde). In this game world, players use their characters to explore locations, defeat creatures and complete quests. By doing this, characters gain experience points. After a set number of experience points have been gained, a character gains a level, giving new skills or abilities and making it possible to explore new areas and attempt new quests. As a player explores new locations, a number of transport shortcuts become available. Players can discover 'flight masters' in newly discovered locations and then use those NPCs in order to fly to previously discovered locations in other parts of the world. Players can also use facilities such as boats and zeppelins in order to move from one of the continents on Azeroth to the other. Players can communicate with each other using text-based chat, separated into different channels for ease of use. When a player instructs their character to yell or say something, a chat bubble appears above their head containing the spoken words in a similar way to a comic book image. A number of facilities are available to characters when in towns and cities. In each major city, characters can access a bank in order to deposit items, such as treasure or crafted items. Each bank is unique to that character, with players able to purchase additional storage space through in-game currency. An addition in the Burning Crusade expansion was the concept of guild banks, allowing members of the same guild to contribute items, resources and in-game currency to a central pool. In the major cities of Azeroth, 'Auction Houses' also exist as a way for characters to sell items to others in a similar way to online auction sites such as eBay. Finally, in almost every town and in every major city are mailboxes. A mailbox can be used to collect items won at auction and also to send messages, items or in-game gold to other characters. A unique feature of this is the ability to send items requiring "cash on delivery", where the receiving character has to pay to accept the item, allowing for sale of items outside of the auction house. Although