What is a web-responsive website?

What is a web-responsive website? The responsive site is the Web browsing CSS based on the screen width, automatically adjust the page p display and layout, to adapt to different size screen optimization browsing experience. First look at a responsive layout site example

Mashable's homepage:
When the browser window is maximized:

To narrow your browser window:

Zoom out again:

Zoom out again:

Popular to say is: Responsive Web site is mainly to consider the PC-side, flat-end, mobile web site self-adaptive design.

As more and more smart mobile devices (such as mobile, tablet device) are added to the Internet, the mobile Internet is no longer a small, independent network, but an important part of the Internet. The advent of Responsive network design (RWD/AWD) is designed to provide a better experience for mobile devices and to integrate various screen sizes and resolutions from the desktop to the phone, using technology to adapt the web to different resolutions from small to large (now to oversized) screens.