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 though IIS 6 is also fine.
PHP: PHP 4.30 is required to run Moodle, but it might be advisable to use PHP 5.24 or higher as this will be necessary in the forthcoming 2.0 version of Moodle.
PHP extensions: Moodle makes use of a number of PHP extensions, most of which are compiled into PHP by default.
Depending on your specific setup, additional software or hardware might be required.