Knockback is a crowd-control status effect in Path of Exile 2 which is most commonly tied to strength-aligned Skills and mechanics.

Knockback is a crowd-control status effect in Path of Exile 2 which is most commonly tied to strength-aligned Skills and mechanics.

Knockback is a status effect that forcibly pushes an entity away from their current position, moving them back to a new location. By default, the Knockback direction is directly away from the entity that caused the Knockback.
The distance that you're able to push Monsters back using Knockback can be improved with modifiers to 'increased Knockback distance', such as the one on the
Clear Space Passive Skill Tree notable. You can also invest into much rarer modifiers that reduce the distance that you're pushed by incoming Knockback from Monster Hits, for example
Hunker Down.
Note: Unique Boss Monsters are immune to Knockback.
A target that is moved by Knockback counts as moving during the Knockback animation.
Tip: you can utilise the Knockback mechanic to enable the bonus Damage of Bleeding!
Knockback cannot be caused by default and instead needs to be enabled by a modifier on a Skill, Support Gem or otherwise. For example the
Armour Breaker Mace Attack Skill causes Knockback on Hit.
Some Monsters that you encounter will have Knockback mechanics known as the 'push' system. An early example of this in the campaign is the Diretusk Boars and Antlion Charger Monsters encountered in the Infested Barrens in Act 3. These Monsters will forcibly push you when engaging you with their charge and roll abilities.
In the case of the Diretusk Boar, their charge ability will push you to the side if it doesn't directly connect with you head on, but it will push and carry you in the direction they're moving if it does connect properly.
Note: many Unique Boss Monsters will cause Knockback with their abilities or movement.
The Punch Through Support Gem applies the Easy Target Debuff to targets Hit by the supported Melee Attack. The next Projectile Attack Hit that deals Damage to the target will consume the Debuff to deal increased Damage based on the expected Knockback distance of the initial Knockback that inflicted Easy Target.
Empire's Grasp are Unique Gloves that have the special modifier 'Knockback direction is reversed'. Any Knockback you inflict while these Gloves are equipped will essentially pull Monsters towards you instead of pushing them away.