This property specifies the language in which the application should display content to end users.
You should configure this property if your application needs to support multiple languages.
The value of this property determines various [internationalization](tutorial-i18n.md) aspects,
including message translation, date formatting, number formatting, etc. For example, the [[yii\jui\DatePicker]] widget
will use this property value by default to determine in which language the calendar should be displayed and how
should the date be formatted. The default value of this property is `en`.
It is recommended that you specify a language in terms of an [IETF language tag](http://en.wikipedia.org/wiki/IETF_language_tag).
For example, `en` stands for English, while `en-US` stands for English (United States).
More details about this property can be found in the [Internationalization](tutorial-i18n.md) section.
#### [[yii\base\Application::modules|modules]]
This property specifies the [modules](structure-modules.md) that the application contains.
The property takes an array of module classes or [configurations](concept-configurations.md) with the array keys
being the module IDs. For example,
```php
[
'modules'=>[
// a "booking" module specified with the module class
'booking'=>'app\modules\booking\BookingModule',
// a "comment" module specified with a configuration array
'comment'=>[
'class'=>'app\modules\comment\CommentModule',
'db'=>'db',
],
],
]
```
Please refer to the [Modules](structure-modules.md) section for more details.
#### [[yii\base\Application::name|name]]
This property specifies the application name that may be displayed to end users. Unlike the
[[yii\base\Application::id|id]] property which should take a unique value, the value of this property is mainly for
display purpose and does not need to be unique.
You do not always need to configure this property if none of your code is using it.
#### [[yii\base\Application::params|params]]
This property specifies an array of globally accessible application parameters. Instead of using hardcoded
numbers and strings everywhere in your code, it is a good practice to define them as application parameters
in a single place and use the parameters in places where needed. For example, you may define the thumbnail
image size as a parameter like the following:
```php
[
'params'=>[
'thumbnail.size'=>[128,128],
],
]
```
Then in your code where you need to use the size value, you can simply use the code like the following:
```php
$size=\Yii::$app->params['thumbnail.size'];
$width=\Yii::$app->params['thumbnail.size'][0];
```
Later if you decide to change the thumbnail size, you only need to modify it in the application configuration
without touching any dependent code.
#### [[yii\base\Application::timeZone|timeZone]]
This property is provided as an alternative way of setting the default time zone of PHP runtime.
By configuring this property, you are essentially calling the PHP function [date_default_timezone_set()](http://php.net/manual/en/function.date-default-timezone-set.php).
For example,
```php
[
'timeZone'=>'America/Los_Angeles',
]
```
#### [[yii\base\Application::version|version]]
This property specifies the version of the application. It defaults to `'1.0'`. You do not always need to configure
