session_start Initialize session data boolsession_start session_start creates a session (or resumes the current one based on the session id being passed via a GET variable or a cookie). If you want to use a named session, you must call session_name before calling session_start. This function always returns &true;. If you are using cookie-based sessions, you must call session_start before anything is output to the browser. session_start will register internal output handler for URL rewriting when trans-sid is enabled. If a user uses ob_gzhandler or like with ob_start, the order of output handler is important for proper output. For example, user must register ob_gzhandler before session start. Use of zlib.output_compression is recommended rather than ob_gzhandler