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docs/guide/structure-entry-scripts.md

 Entry Scripts
 =============
 
-> Note: This section is under development.
+Entry scripts are the first chain in the application bootstrapping process. An application (either
+Web application or console application) has a single entry script. End users make requests to
+an application by accessing its entry script.
+
+Entry scripts for Web applications must be stored under Web accessible directories so that they
+can be accessed by end users. They are often named as `index.php`, but can also be any other names,
+provided Web servers can locate them. For example, the URL `http://hostname/index.php` will execute
+the entry script `index.php`.
+
+Entry scripts for console applications are usually stored under the [base path](structure-applications.md)
+of applications. They are often named as `yii` (with the `.php` suffix) and should be made executable
+so that users can run console applications with command `./yii <route> [arguments] [options]`.
+
+Entry scripts mainly do the following work:
+
+* Define global constants;
+* Register [Composer autoloader](http://getcomposer.org/doc/01-basic-usage.md#autoloading);
+* Include the [[Yii]] class file;
+* Load application configuration;
+* Create and configure an [application](structure-applications.md) instance;
+* Call [[yii\base\Application::run()]] to process the incoming request.
+
+The following is the code in the entry script for the [Basic Web Application Template](start-installation.md).
+
+```php
+defined('YII_DEBUG') or define('YII_DEBUG', true);
+defined('YII_ENV') or define('YII_ENV', 'dev');
+
+// register Composer autoloader
+require(__DIR__ . '/../vendor/autoload.php');
+
+// include Yii class file
+require(__DIR__ . '/../vendor/yiisoft/yii2/Yii.php');
+
+// load application configuration
+$config = require(__DIR__ . '/../config/web.php');
+
+// create, configure and run application
+(new yii\web\Application($config))->run();
+```
+
 
 Configuring options in the bootstrap file
 -----------------------------------------
@@ -29,3 +69,37 @@ During development, you can change this to `true`:
 define('YII_DEBUG', true); // Development only
 defined('YII_DEBUG') or define('YII_DEBUG', false);
 ```
+
+
+The entry script is the bootstrap PHP script that handles user requests
+initially. It is the only PHP script that end users can directly request to
+execute.
+
+In most cases, the entry script of a Yii application contains code that
+is as simple as this:
+
+~~~
+[php]
+// remove the following line when in production mode
+defined('YII_DEBUG') or define('YII_DEBUG',true);
+// include Yii bootstrap file
+require_once('path/to/yii/framework/yii.php');
+// create application instance and run
+$configFile='path/to/config/file.php';
+Yii::createWebApplication($configFile)->run();
+~~~
+
+The script first includes the Yii framework bootstrap file `yii.php`. It
+then creates a Web application instance with the specified configuration
+and runs it.
+
+Debug Mode
+----------
+
+A Yii application can run in either debug or production mode, as determined by
+the value of the constant `YII_DEBUG`. By default, this constant value is defined
+as `false`, meaning production mode. To run in debug mode, define this
+constant as `true` before including the `yii.php` file. Running the application
+in debug mode is less efficient because it keeps many internal logs. On the
+other hand, debug mode is also more helpful during the development stage
+because it provides richer debugging information when an error occurs.