Responsive web pages are so named because they respond to how they are being viewed. They can respond either to the size of the window being used to view them or the type of device being used (pc, tablet, mobile). The page will change its layout so that the content is displayed differently according to the screen/window size ensuring that users will always get the most out of your website no matter how they access it. 


Webzai has added the most popular resposive viewports by default (1024, 768, 480 and 320 pixels wide) but you can also add viewports of any size.


Click here for an example of a responsive website.