Responsive Web Design (RWD) or Web Mobile-friendly is a website production technique, which allows for sites that automatically adapt to the width of the screen.
When there is less space width, you can put blocks under side by side. In this case, instead of positioning the top to bottom.
We can also consider that some smaller blocks are useless on mobile and make them disappear (you will notice the gray block no longer appears in the mobile version). It is also possible, conversely, show new blocks and mobile navigation tools if desired.
Responsive Web Design can be applied to other uses a website. Anything that uses web technologies can be thought responsif:
To understand the principle, the best is to look at how a responsif website adapts to the width of the screen, you can test through the link : http://www.mikweb.ma/demo/
You can read the following document to understand the importance of Responsive Web Design (RWD) for a website : Web Mobile-friendly Advantages
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