Following UML  describes the key concepts of this pattern:
- Client is coding on Interface not class, which make the client decoupled from concrete product type
- Factory encapsulates the creation detail of the product, which make any change of creation is transparent to client
The next question is how does Client tell the Factory to create different Product? There are several ways:
- pass a parameter to the Factory
- register the product into Factory, using Reflection, etc.
- Factory design pattern with abstractions(Factory Method): create Factory for each Product