Below you find a short summary of Drupal, some 3rd party extensions and other techs nodeX brings into action to create websites. It's by far not complete and doesn't pay respect to all hard-working developers in the open source community. I'm truly sorry for that.
Drupal
Drupal is a free and open-source content management framework written in PHP and distributed under the GNU General Public License. It is used as a back-end framework for at least 2.1% of all Web sites worldwide ranging from personal blogs to corporate, political, and government sites including WhiteHouse.gov and data.gov.uk. It is also used for knowledge management and business collaboration. [Source: http://en.wikipedia.org/wiki/Drupal ]
Panels
Every since the begining nodeX is making use of Panels for page layouts and rendering. Panels in combination with Panelizer and the Panels In-Place-Editor (IPE) improves user experience for site builders, managers and editors
Bootstrap
Bootstrap is the most popular HTML, CSS, and JS framework for developing responsive, mobile first projects on the web. [...] makes front-end web development faster and easier. It's made for folks of all skill levels, devices of all shapes, and projects of all sizes. [Source: http://getbootstrap.com
Commerce
Drupal Commerce is used to build eCommerce websites and applications of all sizes. At its core it is lean and mean, enforcing strict development standards and leveraging the greatest features of Drupal 7 and major modules like Views and Rules for maximum flexibility.
Any questions?