Java: Upcasting and Dynamic Dispatch

They provide a contract for classes. Frame the concept in practical terms so you can explain it during interview discussion.

Interfaces in Java provide a way to define a contract that classes must adhere to, ensuring certain methods are implemented. This allows for a form of multiple inheritance, where a class can implement multiple interfaces. For example, an `Order` interface might require a `process()` method, ensuring any class implementing `Order` provides this functionality, promoting consistency across different types of orders.