Zend Optimizer is the run-time needed to be installed on the web server in order to enable it to run PHP scripts encoded by Zend Guard or the legacy Zend Encoder. The run-time is compatible with apache and IIS web servers and it can run on many platforms such as Microsoft Windows, MacOS, and the Linux family. Installing Zend Optimizer also gives you the advantage of running your regular un-encoded PHP scripts at a faster speed. The official Zend website published many results for experiments that proved that their Optimizer can execute PHP file 2 to 10 times faster than without the extension. Zend Optimizer installs itself into PHP.ini as a php extension and is automatically installed with many products such as Cpanel's easyapache, Helm, Plesk, Zend Core and more. Zend Optimizer usually requires root access for Linux servers or Windows user account with administrative privileges in order to be installed using the linux or windows installers but an experienced user can manually install it on a shared webhosting account if the webhosting company allows the use of user's specified custom php.ini file or via .htaccess file. The software supports both PHP version 4.x and 5.x. The configuration can be set directly in the php.ini file and allows you to control the different optimization settings.