🎯 1. What is an Interface?

An interface is a contract that defines WHAT must be done, not HOW.

It contains method declarations (no body) that the class must implement.

💡 Think of an interface as a 100% abstract blueprint.

Example (real world):

A “RemoteControl” interface defines:

• turnOn()
• turnOff()
• changeChannel()

Different devices implement it differently.

⭐ 2. Why Interfaces Exist?

Interfaces provide:

✔ Total abstraction

✔ Loose coupling

✔ Multiple inheritance

✔ Flexible architecture

✔ Standard rules for classes

Java cannot do multiple inheritance with classes, but it can with interfaces.