The Abstract class specifier declares the class as an "abstract base class", preventing the user from adding Actors of this class to the world in Unreal Editor or creating instances of this class during the game.

This is useful for classes which are not meaningful on their own. For example, the ATriggerBase base class is abstract, while the ATriggerBox subclass is not abstract - you can place an instance of the ATriggerBox class in the world and have it be useful, while an instance of ATriggerBase by itself is not useful.


class AActor : UObject