Test04 Sierpie? 2020, 10:34ABC
Declaring class properties or methods as static makes them accessible without needing an instantiation of the class. A property declared as static cannot be accessed with an instantiated class object (though a static method can).
For compatibility with PHP 4, if no visibility declaration is used, then the property or method will be treated as if it was declared as public.
Because static methods are callable without an instance of the object created, the pseudo-variable $this is not available inside the method declared as static.