Terminology
Honorable Kill (HK) - An honorable kill is gained when you kill an opposing faction member of a similar level. This varies and is very similar to the experience point system. Characters who are more than 12 levels lower than yourself at level 60 will not give you any HKs. This scales down slightly for lower level players. HK’s give players Honor Points (HP) which are essential for progression in the PvP ranking system.

Honor Points (HP) - Honor points were formerly known as contribution points. Once a player obtains a HK he will be assigned some honor points. Honor points can be gained in three ways : (1) Killing players of a similar level to yourself. (2) Killing racial faction leaders. (3) winning objectives in battlegrounds / killing NPCs in Battlegrounds.

A level 60 player killing another level 60 player will get more honor points than a level 30 player killing another level 30 player. The only NPCs which give out honor are special faction NPCs you cannot gain honor from killing normal mobs / or normal NPCs.

Dishonorable Kill (DK) - A Dishonorable kill is obtained by killing a low rank NPC character from the opposing faction. These characters are usually quest givers, vendors etc. DK’s reduce your PvP ranking significantly so they should be avoided at all costs. More on Dishonorable kills later on.

Mobs - Mobs is a term used to describe PvE opponents, for example spiders, kobolds, orcs etc. A mob is any computer controlled opponent.

PvP Ranking System - Players who compete in battlegrounds and who hunt down and kill players on the opposing faction will move up rank. The first level is rank 1, all the way upto rank 14. It should be noted that it is very difficult to do well in the PvP system unless you are very high level, 60 is recommended. That’s not saying that your task to get to rank 14 at level 50 is not impossible, its just it is very difficult and that your time would be best spent obtaining a high level before you participate in the PvP system full time.

Battlegrounds - Currently there are two Battlegrounds. Alterac Valley is located in Alterac and can be entered from either on site in person, or you can sign up through a Battele master at either Iron Forge (Alliance) or Ogrimmer (Horde) Warsong Gulch can be found on the border of Ashenvale forest and the Barrens and can be entered in a similar fashion.

Warsong Gulch - This is a 10V10 capture the flag style battleground on a fairly small map. This Battleground is designed for very fast play and can usually be won in around the 15-45 minute mark. More on WSG later on.

Alterac Valley - This is a 40 man V 40 man battleground and is designed for more strategic play where players can capture guard towers, graveyards and call in air strikes. Alterac takes a lot longer to complete, anywhere from 1 hour 15 to 6 hours depending on your team. It is also advisable to join Alterac during peak time as on some servers it can be hard to get in due to the 60 players required to start one.

Special Note on DKs ( by request)
(Q) I was in a raid group and my teammates killed a civilian & I got a DK, = (
Ok, there is only one way to get a DK. That is you must of taken part in killing the civilian. Case closed, however the following counts as taking part :

Healing a team mate who caused damage to the civilian, buffing a team mate who attacks a civilian , effects like sap, fear etc if used before the civilian dies.

If you just sit there and don’t do anything you will not get a DK. So if you group with random players on a frequent basis just be sure to double check who you are healing or damaging / in case they are going for civilians.

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
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.