ScriptFun

$GLOBAL - Used to access global variables from anywhere in the PHP script

<!DOCTYPE html>
<html>
<body>

<?php
$x = 75;
$y = 25;

function addition() {
   $GLOBALS['z'] = $GLOBALS['x'] + $GLOBALS['y'];
}

addition();
echo $z;
?>

</body>
</html>

$_SERVER - Holds information about headers, paths, and script locations
<!DOCTYPE html>
<html>
<body>

<?php
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'];
?>

</body>
</html>

$_REQUEST - Used to collect data after submitting an HTML form

<!DOCTYPE html>
<html>
<body>

<form method="post" action="<?php echo $_SERVER['PHP_SELF'];?>">
Name: <input type="text" name="fname">
<input type="submit">
</form>

<?php
$name = $_REQUEST['fname'];
echo $name;
?>

</body>
</html>