$_POST
Variable
$_POST
variable is used to collect values from a form with method="post"
$_POST
variable is an array of variable names and values sent by the HTTP POST method.
Information sent with the POST method is invisible to others and has no limits on the amount of information to send.
$_GET
Variable
$_GET
variable is used to collect values from a form with method="get"
$_GET
variable is an array of variable names and values sent by the HTTP GET method.
Information sent from a form with the GET method is visible to everyone (it is displayed in the browser’s address bar) and it has limits on the amount of information to send (max. 100 bytes).
The predefined variable $_SERVER
gives the server and execution environment information.