Just in case you wonder what the practical use of the namespace keyword is...

It can explicitly refer to classes from the current namespace regardless of possibly "use"d classes with the same name from other namespaces. However, this does not apply for functions.

Example:

<?php
namespace foo;
class Xyz {}
function abc () {}
?>

<?php
namespace bar;
class Xyz {}
function abc () {}
?>

<?php
namespace bar;
use foo\Xyz;
use foo\abc;
new Xyz(); // instantiates \foo\Xyz
new namespace\Xyz(); // instantiates \bar\Xyz
abc(); // invokes \bar\abc regardless of the second use statement
\foo\abc(); // it has to be invoked using the fully qualified name
?>

Hope, this can save someone from some trouble.

Best regards.

Difference between __NAMESPACE__ and keyword 'namespace' that I find relevant is when invoking a class:<?phpnamespace MyApp;class App {    static function app(){        echo 'hello app';    }}// this will work:$obj = new namespace\App::app();// this will not work$obj = new __NAMESPACE__\App::app();// however this will work:$obj = __NAMESPACE__ . '\App';$obj::foo();?>