A number of facilities are available for characters while in towns and cities. In each major city, characters can access a bank to deposit items, such as treasure or crafted items. Each character has access to personal bank storage with the option to purchase additional storage space using in-game gold. Additionally, guild banks are available for use by members of a guild with restrictions being set by the guild leader. Auction houses are available for players to buy and sell items to others in a similar way to online auction sites such as eBay. Players can use mailboxes, which can be found in almost every town. Mailboxes are used to collect items won at auction, and to send messages, items, and in-game money to other characters.
Intent on settling in Durotar, Thrall's Horde expanded its ranks by inviting the undead Forsaken to join orcs, tauren, and trolls. Meanwhile, dwarves, gnomes, and the ancient night elves pledged their loyalties to the Alliance, guided by the human kingdom of Stormwind. After Stormwind's king, Varian Wrynn, mysteriously disappeared, Highlord Bolvar Fordragon served as Regent but his service was affected by the mind control of the black dragon Onyxia, who ruled in disguise as a human noblewoman. As heroes investigated Onyxia's manipulations, the ancient elemental lord Ragnaros resurfaced to endanger both the Horde and Alliance. The heroes of the Horde and Alliance defeated Onyxia and sent Ragnaros back to the Elemental Plane.
Some of the challenges in World of Warcraft require players to group together to complete them. These usually take place in dungeons—also known as "instances"—that a group of characters can enter together. The term "instance" comes from each group or party having a separate copy, or instance, of the dungeon, complete with their own enemies to defeat and their own treasure or rewards. This allows a group to explore areas and complete quests without others interfering. Dungeons are spread over the game world and are designed for characters of varying progression. A typical dungeon will allow up to five characters to enter as part of a group. Some dungeons require more players to group together and form a "raid" of up to forty players to face some of the most difficult challenges. As well as dungeon-based raid challenges, several creatures exist in the normal game environment that are designed for raids to attack.
Han pasado cinco años desde los eventos narrados en Warcraft 3. La Alianza y la Nueva Horda viven en un estado de guerra fría, y mantienen una frágil y quebradiza paz, mientras reconstruyen sus reinos y tratan de recuperar su prosperidad. En Ventormenta, el rey Varian Wrynn ha desaparecido en circunstancias misteriosas mientras viajaba en misión diplomática a la isla de Theramore, por lo que en su ausencia, es nombrado rey su hijo Anduin Wrynn, todavía un niño, asumiendo la regencia lord Bolvar Fordragon y la misteriosa lady Katrana Prestor. En Orgrimmar, el jefe de guerra Thrall lucha por sacar adelante a la Nueva Horda.