What is responsive web design?

Responsive web design facilitates the build of a single site that will work across multiple screen resolutions. For example, a responsive website may display in multiple columns when viewed on a desktop/laptop but automatically scale to two columns when accessed via a tablet and one column via a mobile phone.

Responsive front end frameworks

Responsive frameworks are grid structures that are used as the building block for scalable websites. It saves time by giving us the building blocks required to build an effective responsive website. In short, it is a set of code that can be reused so that developers are not constantly reinventing the wheel.

Responsive frameworks are Bootstrap, Base, The Responsive grid System, Foundation etc.