What is Responsive Web Design (RWD)? They say it was the biggest development in the history of the internet. Why? It´s a big world out there and people love the internet. People have figured out how to use the internet in ways that I can´t even believe.
The use of cell phones, mobile devices has sky rocketed. In India, more people have cell phones than toilets (that is actually true).
Now, When you develop at site, you can code 40 different pages to show up well on each devise, or, you can use Responsive Web Design code methods to write the code for one page, and it shows up the same (kind of) on each viewers device.
So What is Responsive Web Design? See the video. One part of the the Bill the Geek, Adobe Dreamweaver CC video tutorial series.