Autoloading & Namespaces in PHP

PHP Standard Recommendation (PSR) 4 is a commonly used pattern for organizing a PHP project so that the namespace for a class matches the relative file path to the file of that class.

For example, if you are working within a project that makes use of PSR-4 and you are dealing with a namespaced class named \Jonathan\SomeBundle\Validator();, you can be sure that the file for that class can be found in this relative location in the file system: <relative root>/Jonathan/SomeBundle/Validator.php.

The use keyword “imports” a given namespace into the current context, allowing you to make use of its contents without having to refer to its full path each time.