A really great feature of PHP it the ability to modify its behavior by altering its configuration file (php.ini).
By having the php.ini file, PHP has made it easier to change how it responds and beh
aves even after it has already been installed. What a pain it would be to have to re-compile every time you realize the need for a configuration change.
The php.ini file really helps make PHP more powerful and more secure as well. This is because you can configure PHP with secure settings until the setting need to change for some reason. Then you can also programmatically alter its behavior to accommodate a particular script file’s needs, on the fly, and returning the settings to normal when you’re done.
When PHP is booting, one of the first things it does is look at the php.ini file. It reads into memory the directives defined with in it. In most cases, when you compile PHP, it puts a copy of the php.ini file in /usr/local/lib/php. This may different depending upon your server.
If you are on a Unix machine, you may be able to type locate php.ini or find / -name php.ini -print and have it tell you the location of the php.ini file. If you have installed it on a Windows machine, use the “Find -> Files or Folders” option from the Start Menu.