The term Responsive Web Design was coined by Ethan Marcotte in an article which recently turned 3 years old. The term advocates for a single and adaptable web design rather than separate layouts depending on the medium in which the content is delivered.
Each phase of the architectural process is more immutable, more unchanging than the last. —Ethan Marcotte.
As Ethan Marcotte states, there is 'an emergent (architectural) discipline called "responsive architecture"'. This architecture reacts to the variable conditions of the space, reconfiguring itself in different modes.
For me, responsive architecture is to immutable architecture as responsive web design is to print.
There is no immutable architectural space anymore. There is no immutable web layout anymore.
Different capabilities of browsers and design techniques make possible responsive designs.
All of this reinforces the desire of the web to focus on content rather than in the medium in which content is delivered. The medium is flexible. The content is capable to react its medium's changes. The content is responsive.
To wrap up, I wrote this code sample. When the web's width is less than than 480px, the h1 and p tags apply different CSS rules:
h1 {
font-size:23px;
}
p {
font-size:16px;
}
@media all and (max-width:480px) {
h1 {
font-size:27px;
color:#db4a38;
}
p {
font-size:24px;
}
}