Use when exposing C++ to Blueprint or calling Blueprint from C++: UFUNCTION(BlueprintCallable), BlueprintPure, BlueprintImplementableEvent, BlueprintNativeEvent, _Implementation, UBlueprintFunctionLibrary, WorldContext, DefaultToSelf, ExpandEnumAsExecs, DeterminesOutputType, latent nodes, FPendingLatentAction, FLatentActionInfo, UBlueprintAsyncActionBase, BlueprintAssignable, UINTERFACE, Execute_, TScriptInterface, UENUM(BlueprintType), CallInEditor, FindFunction, ProcessEvent. Also use when the user mentions 'expose to Blueprint', 'custom Blueprint node', 'async Blueprint node' or 'meta specifier'. For reflection and container basics, see ue-cpp-foundations; for details …