For Moodle, you must have the following components up and running on your server:
Database: MySQL (version 4.1.6 or later), PostgreSQL (version 7.4 or later), Microsoft SQL Server (version 2005 or later), Oracle (version 8 or later).
Web server: Apache is the preferred web server.
PHP: PHP 4.30 is required to run Moodle. But it is advisable to use PHP 5.24 or higher, which will be necessary in the forthcoming 2.0 version of Moodle.
PHP extensions: Moodle makes use of number of PHP extensions most of which are compiled into PHP by default.
Depending on your specific setup, additional software and hardware might be required.