Commonly used global variables in php

echo $_SERVER['PHP_SELF'],'
'; //The address of this page
echo $_SERVER['HTTP_REFERER'],'
';//Link to the previous page of the current page The address of
echo $_SERVER['SCRIPT_FILENAME'],'
'; //The absolute path of the current script
echo $_SERVER['REMOTE_ADDR'],'
'; //The IP address of the client
echo $_SERVER['QUERY_STRING'],'
';//Query string,? The following part
echo $_SERVER['DOCUMENT_ROOT'],'
'; //Document root directory
echo $_SERVER['SERVER_ADDR'],'
';//Server's ip

The above introduces the commonly used global variables in PHP, including related content. I hope it will be helpful to friends who are interested in PHP tutorials.