I have a form where the user enters his info (file1.php)
When the user hits submits he is sent to (file2.php) where it displays all his info he then has to hit submit again to confirm. He is then sent to (file3.php) where all his info is submitted to the database and displays a thank you messages.
My question what is the best way to stop the user (when he is at file3.php) to hit the back button and hit submit again? I would like it if he was to hit the back button he would get an error message and a link to the main page.