session question

Hi, I have an "index.php" page which does not user session_start(); command. However in this "index.php" page, there are some $_SESSION['...']; variables stored. How is it possible that $_SESSION['...']; works even if no session has been created before ? moreover, if i use a print "Session ID : ".session_id(); after those lines, session_id() is empty (which is logical) as no session_start(); command has been used before. So, how is it possible that $_SESSION['..'] works ? Do i have a session created or not ? -- Alain ------------------------------------ Windows XP SP2 PostgreSQL 8.1.4 Apache 2.0.58 PHP 5