In this tutorial I will explain how to create a progress bar for PHP file uploads. There is no method built into PHP for returning the status of an upload in progress, so this requires a module called the Alternative PHP Cache (APC). This allows you to store data across sessions and includes built-in functionality for storing/returning file upload stats.
Installing APC is beyond the scope of this tutorial, so visit the APC Installation page for help or talk to your host. To find out if APC is installed already, create a PHP file on your site containing "<?php phpinfo(); ?>", visit it in your browser, and look for a section titled 'APC.' If it is present, then it is installed.