The factory pattern is a class that has some methods that create objects for you. Instead of using new directly, you use the factory class to create objects. That way, if you want to change the types of objects created, you can change just the factory. All the code that uses the factory changes automatically.
It refers to the newly created object through a common interface
When developing larger, more complex systems though, object creation can become difficult. There are situations where different objects may need to be created based on different conditions or based on the context of the object creating it. Creating objects of concrete types explicitly in code can make these situations a nightmare when it comes time to make revisions and additions. When a new class is introduced, you get to follow a trail of code and commence the hours of debugging that will inevitably follow such an endeavor.
The Factory Method pattern defines an interface for object creation but defers the actual instantiation to subclasses.