Created originally by developers from Twitter, the Bootstrap CSS Framework has become one of the most used open source projects by web developers, because it allows developers to create themes and web applications very quickly.

Bootstrap makes back-end and front-end developers equally happy. Back-end devs gain enough autonomy to create simple but visually pleasant pages, whereas front-end developers are able to fully customize a theme, harnessing the power of a well-written code with a great Drupal integration.