For some, the creation of what we now know as RWD is often associated with Ethan Marcotte, although its true origins date from earlier when the site Audi.com was first created, which had an adaptive viewport area as a result of limitations within IE at the time.
If one had to describe what RWD is, then Ethan sums it up perfectly:
Rather than tailoring disconnected designs to each of an ever-increasing number of web devices, we can treat them as facets of the same experience. We can design for an optimal viewing experience, but embed standards-based technologies into our designs to make them not only more flexible, but more adaptive to the media that renders them. In short, we need to practice responsive web design.
In a ...