Why build websites using Drupal?

Drupal is a highly modular, open-source Content Management System (CMS) that enables communities of users to easily publish, manage and organize a wide variety of content on their own websites. Tens of thousands of people and organizations are using Drupal to power community web portals, discussion sites, corporate web sites, intranet applications, and e-commerce applications.

High profile Drupal-based websites include:

Government:

Belgium, New Zealand, US www.recovery.gov

Education:

Harvard, Cornell, MIT, Sun Microsystems Learning Exchange

Politics:

Mike Bloomberg, Hillary Clinton

Entertainment:

ABC Family, Beyonce, Led Zeppelin, Metallica, REM, Pink, J-Lo, Britney Spears, Ozzy Osbourne, Universal Music, Warner Brothers Records, Sony Musicbox, MTV UK, The Onion

High Tech:

America Online, Ubuntu, Nokia, Symantec, SourceForge, Novell, Mozilla Thunderbird, Yahoo Research, Eclipse (the open source IDE), Second Life, NASA APPEL, Adobe Flex

News:

Forbes, Fast Company, Popular Science, Us magazine, Die Zeit, FedEx news site

E-Commerce:

Sanyo-Australia

Civic Organizations:

Amnesty International, Oxfam International, NATO, United Nations, a variety of churches and Scout troops

Source: http://buytaert.net/tag/drupal-sites, http://egressive.com/who-uses-drupal, http://websites.usandv.com/who-is-using-drupal

Core Drupal features include main content ('nodes'), customizable sidebar content ('blocks'), a menu system; content search, user registration, login, and management; administration, blogging, forums, online "books", workflows, tracking and statistics. In addition, there are over 3,000 modules that provide a broad spectrum of capabilities, such as calendars, signup tracking, user-customizable forms, and integration with third-party resources such as amazon.com, Twitter, deli.cio.us, digg, iTunes, paypal, moodle, OpenID, SMS gateways, Weather Underground, and Google Analytics. A salesforce.com module is currently under development.

Drupal is built on php (4 or 5) and either mysql or postgresql, and uses either smarty or phptemplate theming engines. The Drupal developer- and user communities are very active and well-managed. Drupal is supported through a variety of books and online resources. The official Drupal website is http://drupal.org.