Experience (Civ5)

== Overview ==
Experience (XP) represents the knowledge of battle and special abilities a military unit gains as a result of additional training, or after experiencing real combat on the battlefield. In the context of Civilization V, experience allows a unit to gain a number of abilities which aren't the result of the unit's basic armament and type, and which help them in different combat or other situations. These abilities make a unit much stronger than other, inexperienced units, and in many situations may mean the difference between winning or losing the battle. Hence, experience is important for all players, but especially so for those attempting a domination victory.
A unit that enters any type of combat (either by attacking an enemy unit or by becoming the target of an enemy attack) and survives it will gain experience. Once the unit has acquired enough XP, your unit will rise in level. At every such instance, you must choose to either heal the unit instantly for 50 HP, or acquire a "promotion" for that unit. There is a large variety of promotions in Civilization V, each of which improves the unit by either giving it special advantages in battle or improving some other gameplay ability of the unit.
== Experience Thresholds ==
The current experience and level of your unit can be seen by hovering your mouse over the blue bar underneath its name. A unit without any experience will be at Level 1 and show 0/10 XP. It will reach Level 2 at 10 XP and be able to choose its first promotion.
The Zulus' unique ability reduces the experience thresholds for their units by 25%, allowing for faster unit promotions.
Level	Normal XP thresholdfrom previous level	Zulus' XP thresholdfrom previous level	Normal XP from 0 XP	Zulus' XP from 0 XP
1 	0 	0 	0 	0
2 	10 	8 	10 	8
3 	20 	15 	30 	23
4 	30 	22 	60 	45
5 	40 	30 	100 	75
6 	50 	38 	150 	113
7 	60 	45 	210 	158
8 	70 	52 	280 	210
9 	80 	60 	360 	270
10 	90 	68 	450 	338
== How to Acquire Experience ==
The main method of gaining experience is through military action.
=== Combat ===
A unit gains XP for surviving a round of combat. The unit doesn't have to win the combat or destroy the enemy to get the experience; it accrues each round of combat action that the unit lives through.
The amount of XP the unit gets depends upon the circumstances of the combat. Generally, units get more XP for attacking than defending, and more for engaging in melee combat than for other types. Here are some numbers (see the Charts and Tables section for a complete list):
* Initiating a Melee Attack (Melee Unit): 5 XP
* Defending against a Melee Attack: 4 XP
* Initiating a Ranged Attack (Ranged Unit): 2 XP
* Defending against a Ranged Attack: 2 XP
Experience gained through combat is increased by 50% for units of a civilization with Military Tradition from the Honor tree.
Note that in order for the unit to gain experience via a ranged attack, it has to actually inflict damage on the enemy! This rule comes into play when attacking cities which are close to falling. Since they can't be reduced below 1 HP, all attacks done after their health falls to 1 will be "useless" - that is, they won't net experience for the attacker.
In addition, once a single unit has accumulated 30 XP, it no longer gets any additional XP from fighting Barbarians. At 1000 XP, units stop gaining XP from attacking cities.
=== Other Methods ===
* Training buildings - When the Barracks, Armory, and Military Academy are present in a city, all units produced or purchased there will receive additional special training in those facilities. Each training building cumulatively provides 15 XP to new units, so a unit produced or purchased in a city with all three buildings will start with 45 XP.
* Other special buildings and Wonders - Some unique buildings also provide XP to units trained in the city. Poland has the Ducal Stable while Assyria has the Royal Library. The Brandenburg Gate World Wonder provides 15 XP to new units.
* Social policies and Ideological tenets - Certain social policies and other special effects may also provide additional XP to units, either at training, or later during combat.
== Expending Experience ==
When a unit has acquired enough XP to receive a promotion, the "Promote Unit" button will flash every time the unit is active. If you click on that button, a list of the promotions available to the unit is displayed. Click on a promotion to choose one. The XP are expended and the unit acquires the promotion immediately.
=== Promotion List ===
There are dozens of promotions available in Civilization V. Some are available to all units, while others can be acquired only by certain unit types. Most promotions are also organized into "trees" - that is, they require that a unit have acquired other promotions before they become available.
If a promotion is available to a unit, it will be listed when you click on the "Promote Unit" button.
== Strategy ==
Units that have acquired several promotions may become much more dangerous than other, non-experienced units. The low-level promotions all concentrate on one particular battle situation improvement, such as Combat Bonuses in a particular terrain type, or against a particular class of units (Mounted, Armored, Air, etc.). Higher-level promotions, however, have some very powerful effects indeed, such as the ability to attack twice in a round, or to heal after performing an action. To get to these, however, your unit will not only have to enter battle frequently, but also survive. Also, keep in mind that the high-level promotions are only available after certain lower-level promotions have been acquired.
The usual strategy when building up the experience of your army is to start off fighting Barbarians. This is a good opportunity to level up your units in the beginning of the game, when you don't have the time to build training buildings. Of course, because a unit may not gain more than 2 levels fighting them, you will eventually have to switch to "live" targets (i.e., other civilizations). At that point you should also build some training facilities, so that your units start with some XP already.
Focus on a particular upgrade path for each unit - make one a rough terrain specialist, another a flat terrain monster. Acquiring all three ranks of these basic promotions without taking others unlocks the more powerful ones the fastest. So, don't take the Drill/Barrage ability, then Shock/Accuracy, then Drill/Barrage again - this will slow down the acquisition of the more powerful promotions.
Protect the units that have managed to acquire high-level promotions! They are your most powerful weapon in normal battles. Keep them away from the "meat grinder," and use other, weaker units in situations when they're certain to die. Use your experienced units to make sure kills or wear down your enemy from afar, or when they're adequately supported and have a secure retreat option.
== See also ==
* Experience in other games