For those of you who do not have much idea about computer speak, in very simple terms Drupal is an open source content management system which is downloadable at no charge. In even simpler terms, it is used in the creation and management of websites on the internet.
It has basic features such as maintenance and registration of user accounts, management of menus and RSS feeds, customization of page layouts and system administration. It is supposed to be easy to use and even those with no computer programming skills should be able to install it and manage it without any problem.
As with many website applications, there are free Drupal themes that can be used by the website administrator to customize the site to their liking. These come in the form of templates, which can be changed and edited to personalize them and make them suitable for your website. For example, you can insert your own photos as home page headers, amongst many other cool and clever tools to make your site look professional.