How can I maintain state across pages using $_POST?

To maintain state across pages with $_POST, you typically use sessions or hidden fields. Sessions allow you to store user data across multiple pages. Here’s how to use sessions:

<?php
session_start();
if ($_SERVER["REQUEST_METHOD"] === "POST") {
    $_SESSION["formData"] = $_POST;
    header("Location: next_page.php");
    exit;
}
?>

In next_page.php, retrieve the data:

<?php
session_start();
if (isset($_SESSION["formData"])) {
    $formData = $_SESSION["formData"];
    echo "Form Data: ";
    print_r($formData);
}
?>

Using hidden fields is another approach, but sessions are generally more secure and flexible for maintaining state across pages.