The phpinfo file outputs a large amount of information about the current state of PHP. This includes information about PHP compilation options and extensions, the PHP version, server information and environment (if compiled as a module), the PHP environment, OS version information, paths, master and local values of configuration options, HTTP headers, and the PHP License.
Because every system is setup differently, phpinfo() is commonly used to check configuration settings and for available predefined variables on a given system.
phpinfo() is also a valuable debugging tool as it contains all EGPCS (Environment, GET, POST, Cookie, Server) data.
To create the file simply add the following line of code to a blank document and name the file phpinfo.php
<?php phpinfo(); ?>
Save the file as phpinfo.php and place it in the desired directory. Lastly, call the script from a browser.