HTTP Authenticaion Query

<?php if (!isset($_SERVER['PHP_AUTH_USER'])) { header('WWW-Authenticate: Basic realm="My Realm"'); header('HTTP/1.0 401 Unauthorized'); echo 'Text to send if user hits Cancel button'; exit; } else { echo "<p>Hello {$_SERVER['PHP_AUTH_USER']}.</p>"; echo "<p>You entered {$_SERVER['PHP_AUTH_PW']} as your password.</p>"; } ?> Dear All, Above is a code example from php.net http://php.net/manual/en/features.http-auth.php What I am left wondering is the SEQUENCE OF FLOW of logic here. Assume a page has ONLY this code. Then the 1st time the if condition will branch into if part ( and not the else ) . Then it will send a header and ask for a username/password pair. When I enter that it is STILL in the IF part. How will it jump to the else part and authorize me UNLESS when I press enter it reloads the page. Maybe I am tired and not thinking straight. Would love to hear a clarification on this. Thank you, Ashim