Drupal is a flexible, free and open-source PHP-based content management system (CMS). It's used by individuals to manage their blogs, large corporations to handle their business sites, and even the White House website, whitehouse.gov, moved to Drupal late in 2009.
This flexibility is key to Drupal's success. Every page on your site can contain many different content types: blog entries, news stories, polls, a web forum, static web content, and more. Other content types can be added to suit your needs. But if you've no web development experience, then don't worry, that doesn't matter - Drupal comes with several themes that you can apply to customise the look and feel of your site, and there are many more freely available online.
Adding custom modules to your site will extend its capabilities even further. Do you need a better thumbnail image gallery, for instance? A private messaging system? A WYSIWYG HTML editor, CAPTCHA option, or two-way video chat tool? There are thousands of modules available, again for free, and these are just a few of the features they offer.
If you're new to the CMS world then it's probably best to start with a more basic site, though, at least until you've learned how everything works. Spend some time browsing the Drupal Documentation and Support sections before you start, too - the manuals are detailed and will help you quickly get your site up and running.