What are the advantages of using private, public, and protected visibility in PHP classes?

Using private, public, and protected visibility in PHP classes helps to control access to class properties and methods. Private visibility restricts access to only within the class itself, while public visibility allows access from outside the class. Protected visibility allows access within the class itself and any subclasses. This helps to enforce encapsulation and maintain the integrity of the class by preventing unauthorized access to its internal workings.

class Example {
    private $privateProperty;
    public $publicProperty;
    protected $protectedProperty;
    
    private function privateMethod() {
        // code here
    }
    
    public function publicMethod() {
        // code here
    }
    
    protected function protectedMethod() {
        // code here
    }
}