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
Once PvP has been enabled by a player regardless of the method, it will remain in effect for five minutes and players from the opposing faction will be able to attack him.
Additionally, Area of Effect spells will not activate PvP. This means that if a player of the opposing faction with PvP enabled walks into your AoE spell effects while you are fighting monsters, your spell will not damage them and activate PvP for you. If your PvP flag is already on, your AoE spell will damage enemy players (those with PvP enabled) as normal.
The whole scoop is that you are not forced to participate in PvP unless you willingly join in such a fight. However, there will be times where some NPCs will not be available because they have been killed by the opposing faction. In such situations, players will have to wait for the NPC to respawn, which typically takes about 5 minutes. Note that it is illegal to camp and kill the same NPC repeatedly.
Player Vs. Player Servers
The PvP server is designed for players who wish to be able to participate in PvP while adventuring throughout the lands. Players from opposing factions will be able to attack each other on sight in most parts of the world, lending to a much more rewarding and exciting experience because you are always constantly in danger of being attacked by other players. This is truly the World of Warcraft, where the races are in constant conflict with each other.
Some players will recognise this system of PvP as being Faction vs Faction (FvF). For the purposes of World of Warcraft, the FvF and PvP mean the same thing, even Blizzard calls their servers "PvP servers", it's just a metter of semantics.
However, there are many things to consider before deciding to play on the PvP server. You will be killed by players 30 levels higher than you. You will be corpse camped. Your questing might be disrupted completely. Hide and seek is a common game. If you are strongly against many of the unfair PvP combats and encounters that will occur randomly whenever Alliance and Horde players see each other, this server is not for you. While all this does sound discouraging, Blizzard has many policies against griefing.
On the PvP server, various zones will be designated as Friendly, Contested or Enemy territories, coloured Green, Orange and Red respectively. When you enter a new zone, you will be informed of its status. The mini-map is also colour coded to indicate who controls the current zone.
Players in friendly territories are safe unless they decide to engage an opposing faction player in combat.
Players in enemy territories will always be at risk and can be attacked by all players that belong in the territory.
All players can be attacked in neutral (contested) territories.
The following actions will enable a player's PvP flag for 5 minutes on the FvF server:
Attacking an NPC of the opposing faction (NPCs with a faction are clearly marked)
Attacking an enemy player
Aiding a player engaged in PvP
Enable PvP by using the /pvp command
Entering or being in a contested or enemy territory
Starting regions between level 1-20 for each faction are designated green while every other region is orange. Whatever is green to you would be red to the opposing faction. The following 11 regions are designated to the two factions, 6 to Alliance and 5 to Horde. All other unlisted regions are Contested. This means that all players should be able to reach level 20 with minimal PvP interference.