When you originally installed PHP onto your server, you configured it with a certain set of modules. Since the PHP software you run on your server changes over time, it makes sense that the modules you’ll require will also change over time.

To install additional modules in PHP, you must recompile it. To do this, you must first cd into the directory where you extracted PHP to when you installed it. You then must get your current configuration by looking in config.nice. You can then add additional options to the command and run it. Then run make and make install. Restart Apache, and your modules should not be installed.

Extensions are similar to modules, except that they can be installed without recompiling PHP. Extensions can either be PECL or PEAR. Installing these extensions is rather simple. Simply run either pecl install extensionname or pear install extensionname then add extension=extensionname to your php.ini file and restart Apache.

Adding modules or extensions to your PHP installation is as simple as that.