> An application module may be considered as a self-contained sub-application that has its own controllers, models and views and can be reused in a different project as a whole. Controllers inside a module must be accessed with routes that are prefixed with the module ID.

So practically, a module can be handled just as an application, with only minor differences.

Supposing you were having a custom component 'foo' in your application:

 
 
```php 
return array(
'basePath'=>dirname(__FILE__).DIRECTORY_SEPARATOR.'..',
'preload'=>array('log'),)
),
``` And you need to move it inside a module called 'bar':
 
 
```php 
return array(
'basePath'=>dirname(__FILE__).DIRECTORY_SEPARATOR.'..',
'preload'=>array('log'),)
//...
``` Now instead of using the component as usual:
 
 
```php 
Yii::app()->foo ``` You need to call it like this from within the module:
 
 
```php 
Yii::app()->controller->module->foo ``` As you can see, your module is indeed just another application, and you can configure any parameters as you'd do with your "root" application. The only organizatory differences are: + a module has a module "entry point", the FooModule which extends CWebModule, whereas the root application is bootstrapped by the framework itself, starting with your entry script (index.php) + the application's SiteController is called inside a module DefaultController