Realm - Wowpedia - Your wiki guide to the World of Warcraft

By A Mystery Man Writer

A realm is an instance of the World of Warcraft (WoW) game world. Realms are hosted on physical devices called server blades (for this reason, the terms "realm" and "server" are often used interchangeably). This prevents any one realm from becoming too crowded and overwhelming its associated server, provides for better connection times by allowing players to connect to local servers, allows for localized communities based on language, and allows different play-styles for different groups of users. Each realm also has its own name, generally taken from an important character, location or group within the Warcraft universe.