Template:AurasNavBarPaladin
This is a page overviewing the various auras available to Paladins, and detailing tips on how to use each one. For more details on each, see the pages relating to each individually. This article is meant to cover the basics, and go into some strategies, and so should be useful to most players in some way.
Introduction
The paladins auras, blessings and seals are the three buffs that combine to give the class the flexibility that it has. The auras themselves are AOE buffs; that is, they affect all party members within 30 yards of the Paladin. A paladin may only have one aura running at one time, however, they are free to cast, with the only cost of changing them being the Global cooldown. As such, it is wise to always have one aura or another running. You may not change auras while silenced or incapacitated, however, they are not counted as magic, and cannot be dispelled.
Further details
There are two important things to note about auras:
Firstly, they do not stack. If two Paladins in a party are using the same aura, only the greater of the two will be in effect, the other is effectively wasted. As with blessings, it is essntial that the Paladins co-ordinate to have two different auras running, rather than overlapping with the same one. In addition, they do not stack with other spells that grant the same benefit; for example the priest's 
[Prayer of Shadow Protection] will render a 
[Shadow Resistance Aura] obsolete. (Note however that Thorns and Retribution Aura DO stack, as one deals Nature damage and the other Holy.)
Secondly, the aura only affects people in the Paladins party, and not the entire raid. As such most raids will tend to separate paladins, so that as many people as possible gain the benefit,k (this is especially useful for the Resistance Auras, when there is a lot of AOE Fire/Shadow/Frost damage going out). It is also possible of course, to place the paladins together so a single party gains the benefit of multiple auras; this technique most commonly places the paladins with the tanks, to ensure they have the added benefits of the extra auras.
Usage
As with all paladin buffs, usage of Auras is highly situational, and it is unwise to always rely on a single aura for all situations. Indeed, switching auras in combat is frequently beneficial, however, it is a hard trick to master, and don't forget to swap back again! However, one thing that may not be immediately obvious is that most auras (in fact, all except Crusader and Sanctity) only benefit a player that is actively under attack (usually your tank). To clarify, the added armour from Devotion Aura is only useful to your combat classes, if your tank is doing their job, the casters will not be under attack and will have no need for it. The same is true for Concentration Aura; if your casters are never attacked, the question of spell interuption will never arise.
If you are soloing, you of course have free choice over your aura. Popular choices are Devotion or Retribution, either for the added damage, or the reflective damage (some would say that the damage dealt by Retribution Aura is greater than that absorbed by Devotion, although it depends of course on the enemy at the time. Note too the diminishing returns on armour, so the damage mitigation from Devotion Aura will not be as great for a Paladin in plate as for a Mage wearing cloth. Concentration Aura is also useful; especially given that for a paladin specced with Spiritual Focus (Tier 2 Holy talent), Concentration Aura makes healing completely uninteruptable in normal combat (stuns, knockdowns, kicks, etc will all still work against you). Alternatively if soloing, a Retribution Paladin may choose Sanctity Aura for the added bonus to Holy damage.
Both in a group and soloing, the elemental resistance auras usually take priority if needed. They are a Paladins only notable resistance against magical damage, and are a boost to all party members, especially since most AOE damage is elemental, and it can be harder to control aggro on casters than other mobs. As noted above, the exception is if you have a priest that can cast Shadow Protection, which frees up the aura for something else.
In a group it is also important that you choose your aura to benefit your tank, if possible. As mentioned above, casters should not be being interupted, so Concentration Aura is unescessary. Again, choose Devotion or Retribution depending on your tanks requests; against bosses the extra armour is often most tempting. The damage caused by Retribution aura however adds aggro to the person being attacked, not the Paladin whose aura it is, and so can benefit the tank in that way. This effect is especially useful if the Paladin himself is tanking; as ALL Holy damage output has its threat increased by 
[Righteous Fury], the aggro caused by the aura, especially against multiple or fast hitting mobs, can be extremely significant. This effect can be further boosted by a second Paladin having Sanctity Aura, but this is just a luxury. Sanctity Aura itself will generally only boost the Paladins in the groups, so only use it if your tank doesn't need another one or if another Paladin requests it (when improved by talents, it adds 6% to healing effects recieved by targets, this might be useful if you healing is struggling, and you can't mitigate the damage with another aura. It is a great secondary aura for a paladin tank, however.)
As mentioned above, tactics change again when in a raid. Most frequently, the Paladins will be placed so as many members as possible get the benefits of an aura, such as the Resistance auras. It is most important however, to make sure the effects cover the tanks; it doesn't matter how great a tank's armour is, if a well place fireball is going to take him out! As stated above, Fire (and other) elemental damage is common, so if you know it's coming, take precautions. Of course, if you know it's not, choose another aura. Let experience be your guide.
I have not touched on Crusader Aura here; it is by its nature only useful out-of-combat. The only thing is to make sure your party is together before using it, or you will leave someone behind. Don't forget, however, to switch to another aura once you dismount.
Talents
The following talents affect auras:
[Improved Devotion Aura] - Protection Tier 1 - Improves the armour of Devotion Aura by 8-40%.*
[Improved Retribution Aura] - Retribution Tier 4 - Increases Retribution Aura damage by 25-50%.
[Improved Concentration Aura] - Protection Tier 4 - Adds 5-15% chance to resist interuption. Also adds 5-15% chance to resist Silence and Interupt effects.
[Improved Sanctity Aura] - Retribution Tier 5 - Adds 3-6% to healing recieved by targets under this aura.
[Aura Mastery] - Increases aura range to 40 yards.
- As an aside, this talent is not recommended for the serious Tankadin. Redoubt will become the superior choice of talent once Blessing of Sanctuary is acquired, and Retribution Aura is usually the aura of choice, due to its reflective aggro.