This pattern suggests to let the subclasses instantiate the needed classes. The factory method defines an interface, but the instantiation is done by subclasses:

The preceding structure depicts a factory method, and an application uses a factory to create subtypes with an interface.

The benefits of using this are as listed:

• Loose coupling: Separates application from the classes and subclasses
• Customization hooks: The factory method gives subclasses a hook for providing an extended version of an object

The impact of using this is that it creates parallel class hierarchies (mirroring each other's structures), so we need to structure in the best possible ways using intelligent children pattern or Defer identification of state variables pattern.