Stun is a type of crowd control that involves preventing an opponent from moving or acting.
Stun effects come in two main categories, activated and random trigger, which are on separate diminishing returns timers. Nevertheless, all Stun effects are all functionally identical; they prevent the target from moving or acting for the duration of the effect. Stun effects do not break on damage.
Activated Stun effects include Rogue's Cheap Shot and Kidney Shot, Druid's Pounce and Bash, Paladin's Hammer of Justice, Hunter's Intimidate and Warrior's Intercept and Concussion Blow. Random trigger Immobilize effects include Warrior and Rogue's Mace Specialization, Hunter's Improved Concussive Shot and Paladins's Seal of Justice.
Stun effects can be removed with a PvP Trinket, as well as Mage's Blink. Hunters within the effects of The Beast Within and anyone under the effect of Free Action Potion and Living Action Potion are also immune to Stun effects for the duration of the effect.