Great topic! Let's talk about Abstract Classes in PHP — a key concept in Object-Oriented Programming (OOP).

? What is an Abstract Class?

An abstract class in PHP is a class that cannot be instantiated on its own. It serves as a blueprint for other classes. You use it when you want to define common behavior that must be shared by child classes, but you don’t want the abstract class itself to be used directly.

? Key Features

• Declared with the keyword abstract.

• Can contain abstract methods (without a body) and concrete methods (with a body).

• Child classes must implement all abstract methods.

• You cannot create an object from an abstract class.

? Example

<?phpabstract class Animal {    // Abstract method (must be implemented by child)    abstract public function makeSound();    // Concrete method    public function eat() {        echo "Eating...\n";    }}class Dog extends Animal {    public function makeSound() {        echo "Bark!\n";    }}$dog = new Dog();$dog->makeSound(); // Outputs: Bark!$dog->eat();       // Outputs: Eating...?>

? Why Use Abstract Classes?

• To force a contract for child classes.

• To share common code in one place.

• To follow clean and structured design in OOP.

? If You Try This...

$animal = new Animal(); // ? Error: Cannot instantiate abstract class Animal

You’ll get an error because abstract classes can’t be instantiated.