PHP » Operators » ::

Syntax:
Class::method()
Class
A class.
property
A property of the class.
method
A method of the class.

References a class.

This operator is used to reference methods in classes.

Examples

Code:
<?php

class MyClass
{
    function getProperty() {
        return "Value";
    }
}

print MyClass::getProperty();

?>
Output:
Value
Explanation:

A method of a class is referenced.