Drupal
Originally developed as a community platform for a student dorm, Drupal has become more of an application framework than just CMS, thanks to its large and active developer community. It fulfils the broadest range of requirements, combining flexibility, scalability, accessibility, and today’s latest web technologies. 38 % of the fortune 50 websites are built with Drupal - it is the third most used CMS in the world.
The biggest difference between Drupal and other content management systems is the reduction of its core to the bare essentials. There is only a handful of modules – mostly deactivated by default – in a standard installation, which provide e.g. teaser lists, configurable content types, a scalable keywording system, and a complex roll/rights system. The core functionality gives clues both about Drupal’s origins and its strengths: community, collaboration, and user generated content.
Every web project is different. Even CMS systems with a great deal of out-of-the-box functionality don’t meet everyone’s or every project’s needs. Drupal’s design takes this into account and goes for maximum reduction of means in its core. All desired functions need to be installed as separate modules. This includes event the organization of content: There is no "menu tree", because content is entered only once and can be displayed in diverse places.
Drupal is therefore more of a „constructions kit for the creation of a CMS“ than a construction kit for a website. It is not suitable for small web presences with minimal functional requirements.