The following table describes useful fields in $_SERVER array in PHP.

Name Description
PHP_SELF Returns the filename of the current script
SERVER_PROTOCOL Name and revision of the information protocol ‘HTTP/1.0‘ or ‘HTTP/1.1′
REQUEST_METHOD Returns the request method used to access (GET/POST/PUT)
REQUEST_TIME Returns the timestamp from the beginning
DOCUMENT_ROOT Returns the root directory under which the current script is executing. This directory is based on server’s configuration.
HTTP_REFERER Returns the page address that referred
HTTP_USER_AGENT Returns the contents of user agent extracted from HTTP header. This information is typically used for identification of user’s browser and operating system.
REMOTE_ADDR Returns the IP address of the current user
REMOTE_PORT Returns the port of the user’s machine
SCRIPT_FILENAME Returns the absolute path of current script
SCRIPT_NAME Returns the path of the current script

If you want to look at all fields in $_SERVER variable, place the following PHP script in the web server and access it using a browser.

<html>
<head>
<title>$_SERVER variable information
</head>
<body>
<h1>Dump of $_SERVER variable</h1>
<pre>
<?php print_r($_SERVER); ?>
</pre>
</body>
</html>