Possibilities: a Drupal site can support any and all needs one might have from a modern website. This includes language support, user management, content management and authoring, media types, emails, news, chat, and also a good support for mobile and other devices.
Flexibility: Drupal is modular. It begins with a core system that is sufficient for the small very basic website. Any additionl functionality can be added by installing a specific software module that provides it. Hence, choosing drupal allows you to start with a small website, and "grow" with it, developing it along as your buisiness expands. For example: You can start with a small catalog site, then add a surfer reccomengations and advice section, and in the third stage add a full online store, allowing your crowd to purchase your product on the website itself. Every stage of this scenario is a stand alone, and you could execute them at any time.
Support: Drupal is free software (GNU licensed), and is maintained according to the free software model. It is constantly being used, developed and improved by programmers and web developers all over the world, who are ceaslessly adding functionality, robustness and generally adding to its diverseness and quality. And more important: unlike proprietary software systems, we are not under any danger of the owner company changing their business plan or closing alltogether, leaving us with an unmaintainable product. Quite the contrary: Drupal evolves in a continous way, grows all the time, and incorporating new technologies as they emerge. A good example is its support for mobile devices.