The term cooldown is defined as a period of wait time before a spell, ability, or item power can be used after a prior spell, ability, or item power. Sometimes referred to by the pseudo-acronym "CD".
For example:
- The time it takes to recharge after a spell has been cast or an ability or item power has started being used. You will not be allowed to cast another spell for the duration of the cooldown period. This is not the cast time, and usually the cast time of a spell or ability is longer than the global cooldown, which means you can begin your next spell immediately after the cast is finished.
- A
[Hearthstone] has a 20 minute cooldown time.
The term cooldown can also refer to an ability with a long cooldown; for example, Save your cooldowns for boss fights.
A shared cooldown is when some spell, item or ability prevents usage of certain others while it is cooling down. It effectively applies the same cooldown to all those that it shares cooldown with.
It is important to know if a spell or item has a shared cooldown, since that is much more limiting than an isolated cooldown. This usually means that you must choose wisely which to use, since you cannot use all within a short time period. For instance, many potions share cooldown with other potions, and some of the warrior's abilities share cooldown, as well as hunter traps.
Some abilities have multiple shared cooldowns. For instance the shaman's 
[Earth Elemental Totem] can only be cast itself once every 20 minutes, can not be cast within 2 minutes of using a 
[Fire Elemental Totem], and triggers a 1 second global cooldown.
Warrior stance changes also fall under the shared cooldown category. Switching stances as a warrior prevents switching to another stance for 1 second but does not prevent the user of other abilities.
Global cooldown
A global or universal cooldown, frequently shortened to "GCD", is the cooldown which starts every time you start to cast a spell, and it affects all of your class spells. There are exceptions to this, however, as noted below. The basic rule of thumb is that if the spell affects the casting of the next spell, it will not activate the global cooldown.
If the spell has a casting time less than the global cooldown (or instant cast), you generally have to wait the remainder of the global cooldown. If a spell with casting time is interrupted before it has finished casting, the global cooldown will be canceled, meaning you can start casting a new one immediately.
The global cooldown is generally 1.5 seconds for all classes except rogues and cat form druids, whose abilities are mostly one second global cooldown. Shaman totems also only trigger a one second global cooldown. The global cooldown affects the wait for the next ability, so using an item or ability with the standard 1.5 second cooldown will require waiting that long before a 1 second global cooldown ability can be used.
Abilities noted for not affecting nor being affected by the global cooldown:
- Druid
- Hunter
- Mage
- Paladin
- Priest
- Rogue
- Shaman
- Troll
- Warlock
- Warrior
Abilities that are affected by but will not themselves trigger the global cooldown:
- Orc's
[Blood Fury] - Paladin's [Hammer of Wrath]
- Paladin's [Avenging Wrath]
- Priest's [Chastise]
- Tauren's Warstomp
- Warlock's [Shadowfury]
Cooldown and usage theory
The cooldown determines how often something (spell, ability, or item) may be used. Specifically, it has an inverse relationship to how many times per fight it may be used.
For example, a druid should never use 
[Rebirth] in the post-encounter resurrection. The druid resurrection spell is on a 20 minute timer and should be used in emergencies only, such as when it can prevent a wipe.
Here's a rough guide to help with when to burn a cooldown:
| Cooldown length | When usable | |
|---|---|---|
| 1.5 sec | GCD | Spammable at will |
| 90 sec | common | Usable often |
| 3 min | common | Usable each battle, sometimes several times during a boss fight |
| 10 min | mildly long | Usable on most tough miniboss fights |
| 30+ min | long | Usable at calculated times and emergencies |
Item cooldowns
Items with cooldowns are simply items that have limit on how often you can use them.
For example 
[Major Healing Potion] has a 2 minute cooldown, so it can be used just once every 2 minutes. The average cooldown is 2 or 5 minutes, but they range from 10 seconds to 3 hours (like [Signet of Expertise]) to 3 days at the longest. These items can be equipped in a variety of slots or used from the backpack.
Most consumable items have a shared cooldown, such as alcoholic beverages.
These items have a long cooldown (this isn't an exhaustive list):
- [Snowmaster 9000] (1 day)
- [Elune's Lantern] (1 day)
- [Mr. Pinchy] (2 days; 3 charges)
Most equippable items with "Use" effects have a 0 second global cooldown.
Tradeskill cooldowns
Several professions have recipes with long cooldowns.
- Alchemy has several transmutes with a shared 20 hour cooldown. [Northrend Alchemy Research] has a 3 day cooldown.
- Enchanting has a 2 day cooldown for [Void Sphere].
- Inscription has separate 20 hour cooldowns for [Minor Inscription Research] and [Northrend Inscription Research].
- Jewelcrafting has two separate 20 hour transmutes for [Icy Prism] and [Brilliant Glass]
- Mining has a 20 hour cooldown for [Titansteel Bar].
- Tailoring has separate 3.83 day cooldowns for [Ebonweave], [Moonshroud], and [Spellweave]
