什么是php超全局变量数组

<form action="process.php" method="get">
  Name: <input type="text" name="name"><br>
  Age: <input type="text" name="age"><br>
  <input type="submit">
</form>
// process.php
$name = $_GET['name'];
$age = $_GET['age'];
echo "Welcome $name! You are $age years old.";

<form action="process.php" method="post">
  Name: <input type="text" name="name"><br>
  Age: <input type="text" name="age"><br>
  <input type="submit">
</form>
// process.php
$name = $_POST['name'];
$age = $_POST['age'];
echo "Welcome $name! You are $age years old.";

<form action="process.php" method="post">
  Name: <input type="text" name="name"><br>
  Age: <input type="text" name="age"><br>
  <input type="submit">
</form>
// process.php
$name = $_REQUEST['name'];
$age = $_REQUEST['age'];
echo "Welcome $name! You are $age years old.";

// send_cookie.php
setcookie('username', 'John', time() + (86400 * 30), "/"); // 设置 cookie
echo 'Cookie sent.