Massively Multiplayer Online Role-Playing Game (MMORPG), as defined today, have only existed since the early 1990s. World of Warcraft (commonly known as WoW) is a MMORPG in which a large number of players interact with one another in a virtual world. As in all Role Playing Games (RPGs), players assume the role of a fictional Character and take control over many of that character's actions. MMORPGs are distinguished from single-player or small multi-player CRPGs (Computer Role Playing Games) by the number of players and by the game's persistent World (persistent player world or virtual world-used as a setting for a role playing game), usually hosted by the game's publisher, which continues to exist and evolve while the player is away from the game. The persistent player world is always available and world events happen continually.
There are two types of characters in the game Player Characters (PCs, or simply "characters") and Non-Player Characters (NPCs). A Player Character is an avatar in the world of Azeroth that is controlled by a player. The color of a PC's name tag can be blue, green, yellow or red depending on faction and Player v/s Player (PvP) status. Non-Player Characters are controlled by the game software and can only interact with PCs through scripted events or artificial intelligence (AI). There are three types of NPCs- Friendly NPCs, Hostile NPCs, Neutral NPCs whose names are displayed in green, red, and yellow. Friendly NPCs cannot attack friendly characters and vice versa. Hostile NPCs can freely attack any PC with whom they are hostile. Neutral NPCs will only attack if provoked.
When creating a character in World of Warcraft, the player can choose from ten different races in different factions for example Alliance and Horde. Race determines the character's appearance, starting location, and initial skill set, called "racial traits". The Alliance currently consists of Humans, Night Elves, Dwarves, Gnomes and Draenei. The Horde currently consists of Orcs, Tauren, Undead, Trolls and Blood Elves. Draenei and Blood Elf characters were introduced in The Burning Crusade, and require that expansion in order to be created. In addition to the ten playable races there are many NPC races including (but not limited to) Goblins, Ogres, Murlocs, and Naga.
The game has nine character classes that a player can choose from like Druid, Hunter, Mage, Paladin, Priest, Rogue, Shaman, Warlock, and Warrior. Though not all classes are available for each race. Each class has a set of unique abilities and talents. Abilities are general skills and spells available to the entire class, while talents allow players to specialize their character and further refine their role. Each class has a set of three talent trees. Depending on class, players may choose to build their character's talent trees for damage-dealing (also called damage-per-second, DPS), healing, tanking, or a mix of these. Some classes, known as "hybrid classes," are able to perform different roles depending on a group's needs
World of Warcraft runs natively on both Macintosh and Windows platforms. Boxed copies of the game use a hybrid CD to install the game, eliminating the need for separate Mac and Windows retail products. The game allows all users to play together, regardless of their operating system.
World of Warcraft uses server clusters allow players to choose their preferred gameplay type and to allow the game to support as many subscribers as it does. There are four types of realms: Normal (also known as PvE or player versus environment), PvP (player versus player), RP (a roleplaying Normal/PvE server) and RP-PvP (roleplaying PvP server).
Users may have up to ten characters per realm and up to a maximum of fifty characters per account. Characters can be moved between realms in the same region (e.g., from one European server to another, but not from a European server to an American one) for a fee.