Drupal is a content management system (also refered to as CMS), meaning Drupal is used to manage content on informational sites, social media sites, member sites, intranets and web applications.
Drupal isn't a CMS, strictly speaking, but a platform into which various modules can be plugged and combined to provide CMS customized to your needs. There are modules for many purposes, for example storing different kinds of content, retrieving content based on criteria, and for displaying content in different ways and much more.
What is it that makes Drupal different from other CMS's?
EPiServer, SiteVision, Sitecore, Polopoly and Escenic are all examples of first generation content management systems. They're characterized by the fact that new or customized functionality is added through development of new modules that are programmed in Java or the .NET platform. This is time consuming and requires help from specialists. In practice, what this results in, is a monopoly-like situation where you become dependent on a limited number of service providers for making even the smallest of changes or development.
Drupal, on the other hand, is a second generation CMS. It means that a lot of new or customized functionality can be created in the user interface without programming. Doing this doesn't take much time and can be done by a member of your staff versed in your operations. This lessens your dependency on service providers offers you the freedom to make simple adjustments and development yourself.
But even Drupal requires programming at one point or another, for purposes like integrating other systems into your own operations. But don't worry, Drupal is also free software with open source, unlike EPiServer, SiteVision et c. This means that Drupal is free (gratis), that you may use or modify Drupal to your heart's desire. It's up to you (no one else!) to decide whether you want to distribute your modifications. The only thing you're expected to do in return is that if you choose to distribute said modifications you make them available under the same terms you obtained Drupal, that is an open source license.
Why should I pick Drupal?
There are four reasons why you should choose Drupal instead of EPiServer, SiteVision, Sitecore, Polopoly, Escenic and other first generation content management systems. Using Drupal you can create solutions that:
- offer shorter time to market for new or improved features on your site.
- empower your staff to customize and further improve your website without relying on a Drupal service provide
- offer sustainable maintenance when many small changes happen that affect functionality as well as design
- lower the total cost of ownership (TCO) as a result of Drupal being free software, offering shorter development time, less dependence on service providers and lower maintenance costs.
Drupal's unique advantages are likely that primary reason why Gartner Group ranks Drupal way ahead of EPiServer with regards to "completeness of vision" as well as "ability to execute".