As was mentioned above, PHP is available for many operating systems and platforms. Therefore, you are encouraged to go to this URL to find the environment that most closely fits the one you will be using and follow the appropriate instructions.
From time to time, you may also want to change the way PHP is configured. To do that you will have to change the PHP configuration file and restart your Apache server. Each time you make a change to PHP’s environment, you will have to restart the Apache server in order for those changes to take effect.
PHP’s configuration settings are maintained in a file called php.ini. The settings in this file control the behavior of PHP features, such as session handling and form processing. Later chapters refer to some of the php.ini options, but in general the code in this book does not require a customized configuration. See http://php.net/manual/configuration.file.php for more information on php.ini configuration.