First, thanks to the author for the great book. I have some limited coding experience (FORTRAN) and would like to learn PHP. Could someone point me to the right direction to understand how php file is executed? Example: Script 13.5 (Logging In). How is possible to check for the email and password (code lines 12-14) when the form to enter that information is defined after it (lines 53-56)? I expected it to be opposite. First to create form (user can enter username/pass) and after that to check if it matches the admin info. I struggle to understand "check if the form has been submitted" meaning. If it was not submitted, how is possible to check it again after user enters username/pass (lines 53-56). Appreciate any help!