If you see in php.ini something like: So, extension - it's native PHP extension zend_extension - it's Zend extension for PHP(mainly using for profiling/debug). Both extension kinds share lots of stuff. The difference between both types is mainly in hooks they register into the Engine. Remember that, despite it is very uncommon, an extension can ... Continue reading What difference between extension, zend_extension, zend_extension_ts in PHP.ini (extension VS zend_extension)?