World of Warcraft PvP
World of Warcraft currently offers 3 types of server for players to play on, each offering a different ruleset in terms of how PvP is implemented in the game. These are called the "Standard Player vs. Environment Server" and the "Horde vs. Alliance Race War Server" which we will abbreviate to PvE and PvP (Player V Player) server respectively. On both servers, players will not able to attack other players on their own faction other than through a duel, keeping in line with the game world and lore.

The PvE servers are further split into two - PvE standard and PvE Role-playing both have the same combat rulesets however players have an expectation to roleplay there character when typing text on a role-playing server. For simplicity in this guide both PvE servers will come under the one heading – PvE.

Player Vs Environment Servers
The PvE server is designed for players who wish to be able to play the majority of the game and quest peacefully without interference from other players, especially from the opposing faction. However, players will still be able to participate in PvP if they choose to do so, particularly in fair PvP battles when Battlefields is implemented. On this server, players from different factions may not attack each other unless the target player's PvP flag is enabled.

The following actions will enable a player's PvP flag on the PvE server:

Attacking an NPC of the opposing faction (NPCs with a faction are clearly marked)
Attacking a player who attacked an NPC
Aiding a player engaged in PvP
Enable PvP by using the /pvp command
Walking into an enemy faction city