An associative array of variables passed to the current script via the HTTP POST method when using application/x-www-form-urlencoded or multipart/form-data as the HTTP Content-Type in the request.
$HTTP_POST_VARS contains the same initial information, but is not a superglobal. (Note that $HTTP_POST_VARS and $_POST are different variables and that PHP handles them as such)
Introduced $_POST that deprecated $HTTP_POST_VARS.
This is a 'superglobal', or automatic global, variable. This simply means that it is available in all scopes throughout a script. There is no need to do global $variable; to access it within functions or methods.
<?php echo 'Hello ' . htmlspecialchars($_POST["name"]) . '!'; ?>
Assuming the user POSTed name=Hannes
The above example will output something similar to:
Hello Hannes!
Please login to continue.