What is Responsive Design?
(a.k.a. Responsive Website Design [RWD], Adaptive Design or Adaptive Websites or Progressive Enhancement)
Responsive Design is a relatively new (~2011) and advanced set of web design techniques that attempts to accommodate various screen sizes and browsers. Responsive Design is particularly targeted at making browsing websites on tablets and mobile devices more user friendly, and can be a good alternative to creating duplicate sites for mobile browsing.