Have you ever wondered about the different type prefixes in Unreal Engine? Like, what’s the different between ASomething, FSomething, ESomething and so on? I know I did when I decided to learn Unreal Engine.

Below is a simple table that defines when to use what prefix.

Prefix	Use case	Example
A	Use for AActor derived classes. These define that the class is an actor that can be placed within a world	ABuilding, AWeaponPickup, AJumpPad
U	Use for UObject derived classes that aren’t actors	UInventoryPlugin, USoundSettings, USkillsSaveGame
E	Use for enums	EStateEnum, EBossType, ECraftingType
T	Use for template functions	TObjectPtr<T>, TWeaPtr<T>, TCustomTemplate<T>
I	Use for interfaces	IInteractable, IPickupable, INotifyReceiver
F*	Use for structs (and others)	FPickupDefinition, FSegmentDefinition, FCustomzationOption

* The F prefix actually stands for float, as in Floating Point. It’s a fun story that Dark-Veil explains on the Unreal Engine forum.