Visibility

Properties, methods and classes may have a visibility. It limits the scope of the definition :

• private : to the current class

• protected : to the current class hierarchy (parents and children classes)

• public : to all the code

In PHP, the default visibility is public.

Visibility may no change, unless when overwriting it with a trait, or in a child class.

<?php

class x {
    public const X = 1;

    private $property;

    protected function foo() {}
}

?>

Documentation

See also PHP OOP Visibility, PHP P51: Visibility Modifiers, PHP Tricks: Access control bypass

Related : Properties, Method, Static Constant