$_server 'http_host' localhost code example

Example 1: php server self

<form action="<?php echo $_SERVER['PHP_SELF']; ?>"> 
//there is no reason to use this to submit form data to the same page
<form action=""> 
//will do the same thing

Example 2: php server name

echo $_SERVER['PHP_SELF'];
echo "<br>";
echo $_SERVER['SERVER_NAME'];
echo "<br>";
echo $_SERVER['HTTP_HOST'];
echo "<br>";
// echo $_SERVER['HTTP_REFERER'];
echo "<br>";
echo $_SERVER['HTTP_USER_AGENT'];
echo "<br>";
echo $_SERVER['SCRIPT_NAME'];