An Attack is the process of attacking.
The process starts with the unit performing it's attack animation. After the Damage Point duration, the Attack Instance is created. If the unit is interrupted during the Damage Point duration, the attack will be canceled. After the Attack Instance has been created, the unit continues its animation, called Backswing Point. The attack animation can be canceled during the Backswing Point in order to reduce the duration the unit is only playing its animtion.
The behaviour of Attack Instances depend on its weapon type. For more information read: Weapon Types
During the lifetime missile-type weapon types travel towards their target unit or point. For the weapon types Melee and Instant this is skipped.
If the attack is succesful, a damage instance is created for every hit target. The damage amount of the damage instance is calculated from the attack damage of the attack instance and the weapon type. In most cases the damage amount of the damage instance is equal to the attack damage of the attack instance, but for area of effect attack instances the damage amount often varies. If the attack failed, the Attack Instance will be destroyed without damaging the target.