XP

Experience Points (XP) are a numerical quantity that dictates your level and your progress in that level. Your experience points are shown (in multiplayer) on the bottom of the screen with a yellow meter. When you gain experience points, it becomes green and resets when you achieve the next level.

The Experience Meter is only available in Call of Duty 4: Modern Warfare, Call of Duty: World at War, and Call of Duty: Modern Warfare 2. Experience points are also available in Call of Duty: United Offensive but there is no experience meter and the ranks reset when you end or exit a match.

Call of Duty: United Offensive
You only have to kill enemy players; destroy bases in the Base Assault gamemode or capture flags. You start as a private-first class and the top rank is Sergeant. The ranks allows you to carry more grenades, satchel charge and a binocular for artillery strike.

Call of Duty 4: Modern Warfare

 * Killing the enemy. You gain 10 points per kill in Team Deathmatch (all forms) and Sabotage. 5 points are earned for killing in Free for All, Headquarters and Domination. You can gain 50 points per kill in Search and Destroy, as no respawns are permitted; the life is worth more. If you kill when using Last Stand perk, double points will be earned. In Headquarters or Domination, you score an extra 5 experience points for kill an enemy who is within an objective capture range (i.e. within a Domination flag).


 * Assisting in the death of an enemy. If you attack an enemy but do not kill him and he dies before his health is fully regenerated you are awarded an assist, 2 experience points for matches which grant 10 exp a kill, 1 for kills which grant 5 exp a kill, and assists are impossible to achieve in Free-for-all mode.


 * Completing challenges. Challenges are a new method to gain experience points. Challenges have some requirements to be fulfilled before the reward is available. For example, for marksman challenges, you need to kill the enemy using the pertinent gun or in expert challenges, you need kill the enemy via headshots with the gun. There are also challenges that require you to do other, more varied tasks, for example, the "think fast" challenge requires you to kill an enemy by directly hitting the enemy with a Fragmentation Grenade.The challenges involving guns gives either attachments or camouflages as an addition to experience points. Other challenges give only experience points.


 * Additionally: The game gives you some bonus points for your performance when the match ends as a "Match Bonus".

Call of Duty: World at War
You can gain experience points in the same manner as you do so in Call of Duty 4: Modern Warfare, but also by:


 * Cooperative (Co-op) gameplay. This is a new mode where you play the missions in normal gameplay but with 2-4 players. You can do exclusive challenges when playing in Co-op. Playing Nacht der Untoten does not gives any experience points. Playing in split screen cooperative mode also does not give any experience points


 * Completing vehicle challenges


 * Reviving a teammate whom is using Second Chance. This gives you 2 points.

For example in Team Deathmatch: 10 points for a kill. 2 assist points for at 20-39% of damage given. 4 assist points for at 40-59% of damage given. 6 assist points for at 60-79% of damage given. 8 assist points for at 80-99% of damage given, includes putting an enemy in Last Stand with a teammate "stealing" the kill.
 * Gaining an assist. This is more complicated than Call of Duty 4: Modern Warfare as the amount of experience points gained is proportionate to the amount of damage inflicted towards the enemy. This is given in multiples of 5ths of the amount of XP given for a kill.

Call of Duty: Modern Warfare 2

 * Base Kill Award - 100 in Deathmatch, 500 in Search and Destroy and 50 in other modes.


 * Payback! - Kill an enemy who has killed you previously. +50XP Getting this for a particular opponent will reset it until they kill you again.
 * Buzzkill! - Kill an enemy who is 1 kill short of acquiring kill streak reward. +100XP
 * Bulls-eye! - Kill an enemy with a throwing knife. +50XP Becomes 0XP at later levels.
 * Flag Runner! - Picked up the flag in a Capture the Flag match. +50XP
 * Stuck! - Stick a Semtex grenade on an enemy. +50XP
 * Rescuer! - Save a wounded teammate +50XP Kill the person attacking him
 * Hijacker! - Steal enemy care package.+50XP Sometimes +100XP, later becomes 0XP
 * First Blood! - Be the first person to score a kill in a match. +100XP
 * Offense! - Kill a defender. +50XP In an objective game, kill an enemy who is near a point/flag they control.
 * Defense! - Kill an attacker while near a point/flag you control in an objective game. +50XP
 * Comeback! - Recover from a streak of deaths. +50-100XP More dependant on amount of deaths in death-streak
 * Position Secure! - Take an objective. +150XP
 * Double Kill! - Kill two enemies at once. +50XP
 * Triple Kill! - Kill three enemies at once. +75XP
 * Multi Kill! - Kill four or more enemies at once. +100XP
 * Longshot! - Kill an enemy from a distance. +50XP
 * Share Package! - A team-mate saved your Care Package from the enemy! Multiples of +50XP dependent on award given. (E.G. Friendlies rescuing an AC-130 will score more for you than if they rescued a UAV)
 * One Shot Kill - Kill an enemy with one shot from a sniper rifle +0 XP
 * Flag Return - You return the flag to it's "base". +50XP
 * Headshot - You kill the enemy with a bullet to the head. +50XP +500XP in Search and Destroy, despite saying +50
 * Crowd Control - Make an excellent distraction (using the riot shield, absorb damage while or not long before someone else kills the enemy firing at you.) +50 for the assist, more for bullet damage absorbed by shield.
 * Afterlife - Kill an enemy while dead. +25XP
 * Assisted Suicide - Injure an enemy before he kills himself (usually due to fall damage). +350XP
 * Execution - Headshot someone who is in Last Stand or Final Stand. +100XP
 * Avenger - Kill an enemy who has killed your team-mate. +50XP very quickly in order to receive bonus
 * Saboteur! - Plant the bomb. +1000 in S&D, +200 in Sabotage and +100 in Demolition.
 * Ninja Defuse - Defuse a bomb while the planter on the opposing team is still alive(On S&D, Sabotage or Demolition). +1000XP - TBC
 * Hero! - Defuse the bomb.
 * Heroic! - Get a capture point while in last stand.