Unable to understand code in config file

[raydona]

Hi,

I'm new to PHP, so please bear with me. I've just downloaded an application. The following is part of PHP code in a config file that came with the application:

// setting up the web root and server root for
// this application
$thisFile = str_replace('\\', '/', __FILE__);
$docRoot = $_SERVER['DOCUMENT_ROOT'];

$webRoot  = str_replace(array($docRoot, 

'library/config.php'), '', $thisFile);
$srvRoot  = str_replace('library/config.php', '', 

$thisFile);

define('WEB_ROOT', $webRoot);
define('SRV_ROOT', $srvRoot);

I don't know what are web root, server root or DOCUMENT_ROOT. Would it be possible to explain what this code is designed to do. Am I required to insert anything or make any alterations? I would be grateful for all help.

[fugix]

looks to me like it places scripts into your document root directory..shouldn't  be tampered with unless the config file is moved to another location