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**Factory Method** is a **creational design pattern** that defines an **interface for creating objects**, but lets **subclasses decide** which class to instantiate.
In other words, it **delegates object creation** to child classes, freeing the main code from being tied to specific types.

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### Why it is needed

Without a factory method, code often creates objects directly with `new`, which makes the system rigid and hard to extend.
Factory Method separates the **creation logic** from the **usage logic**, which lets you add new product types without changing the client code.

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### Structure

1. **Product** - a common interface for all created objects.
2. **ConcreteProduct** - specific implementations of the product.
3. **Creator** - declares the factory method that returns a `Product` object.
4. **ConcreteCreator** - overrides the factory method, creating the needed product type.

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### Example (Java)

```java
// Product
interface Transport {
    void deliver();
}

// Concrete products
class Truck implements Transport {
    public void deliver() {
        System.out.println("Delivery by land");
    }
}
class Ship implements Transport {
    public void deliver() {
        System.out.println("Delivery by sea");
    }
}

// Creator
abstract class Logistics {
    abstract Transport createTransport();

public void planDelivery() {
        Transport t = createTransport();
        t.deliver();
    }
}

// Concrete creators
class RoadLogistics extends Logistics {
    Transport createTransport() { return new Truck(); }
}
class SeaLogistics extends Logistics {
    Transport createTransport() { return new Ship(); }
}
```

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### Advantages

- Frees the code from a hard dependency on specific classes.
- Simplifies extension: you can add new product types without changing the client code.
- Improves testability and flexibility.

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### Disadvantages

- Increases the number of classes in the project.
- Requires inheritance, which is not always convenient.

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**Summary:**
Factory Method is a way to **move object creation from client code into subclasses**, preserving the flexibility and extensibility of the architecture.

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