How can PHP developers prevent users from manipulating data by refreshing the page?

To prevent users from manipulating data by refreshing the page, PHP developers can use a technique called "Post/Redirect/Get." This involves processing form submissions using POST requests, redirecting to a new page using GET requests after processing the form data, and ensuring that refreshing the page will not resubmit the form data.

// Check if the form has been submitted
if ($_SERVER["REQUEST_METHOD"] == "POST") {
    // Process the form data
    // Redirect to a new page using GET request
    header("Location: success.php");
    exit;
}