Below is the translation of your text into English, including the explanation of PHP functions and server variables:
PHP functions and server variables for obtaining the current URL path:
The code is as follows:
```php
"; // Get the server document root variable
echo $_SERVER['PHP_SELF'].""; // Get the variable for the absolute server path of the file executing this code
echo __FILE__.""; // Get the variable for the absolute file system path of the file
echo dirname(__FILE__); // Function to get the folder path where the file is located
?>
```
### Explanation:
1. `$_SERVER['DOCUMENT_ROOT']`: This retrieves the root directory of the server where the website files are stored.
2. `$_SERVER['PHP_SELF']`: This returns the path and filename of the currently executing script relative to the web root.
3. `__FILE__`: This magic constant returns the absolute filesystem path of the current file.
4. `dirname(__FILE__)`: This function returns the directory name of the file path provided by `__FILE__`.