$_SERVER["DOCUMENT_ROOT"] === /home/user/www
$_SERVER["SERVER_ADDR"] === 143.34.112.23
$_SERVER['HTTP_HOST'] === example.com (or with WWW)
$_SERVER["REQUEST_URI"] === /folder1/folder2/yourfile.php?var=blabla#123
__FILE__ === /home/user/www/folder1/folder2/yourfile.php --->//p.s. ON WINDOWS SERVERS, instead of / is
basename(__FILE__) === yourfile.php
__DIR__ === /home/user/www/folder1/folder2 [same: dirname(__FILE__)]
$_SERVER["QUERY_STRING"] === var=blabla#123
$_SERVER["REQUEST_URI"] === /folder1/folder2/yourfile.php?var=blabla#123
parse_url($_SERVER["REQUEST_URI"], PHP_URL_PATH) === /folder1/folder2/yourfile.php
$_SERVER["PHP_SELF"] === /folder1/folder2/yourfile.php
//if "parentfile.php" includes this "yourfile.php"(and inside it are the codes written), and "parentfile.php?a=123" is opened, then
$_SERVER["PHP_SELF"] === /parentfile.php
$_SERVER["REQUEST_URI"] === /parentfile.php?a=123
$_SERVER["SCRIPT_FILENAME"]=== /home/user/www/parentfile.php
str_replace($_SERVER["DOCUMENT_ROOT"],'', str_replace('\','/',__FILE__ ) ) === /folder1/folder2/yourfile.php
