What is the difference between using "protected" and "private" functions in PHP classes?

Using "protected" functions in PHP classes allows those functions to be accessed within the class itself and any classes that extend it. On the other hand, using "private" functions restricts access to only within the class they are defined in, making them inaccessible to any classes that extend it. It is important to choose between "protected" and "private" based on whether you want the function to be accessible to subclasses or not.

class ParentClass {
    protected function protectedFunction() {
        // code here
    }
    
    private function privateFunction() {
        // code here
    }
}

class ChildClass extends ParentClass {
    // Can access protectedFunction but not privateFunction
}