DynamicCall is an ActiveX DLL that lets you call functions from dynamically loaded libraries (DLLs). This is impossible to do directly in Visual Basic. With DynamicCall you can use a library even if you don't know its name at design time, or use a heavy library and unload it when it is not needed anymore, or you can delete a library after using it (in VB you cannot do this since the library is not freed until the end of the program). With DynamicCall you can also call a function by its address (commonly known as 'callback').