Responsive web design (RWD) is an approach to web design that attempts to adapt a site's design for optimal viewing on all of a customer's devices.
RWD helps wed designers and site owners create an"edit once, display anywhere" website.
The web designer builds one page that can then be viewed on a wide-screen desktop or a smallscreen cell phone without requiring the user to open another site or page.
Instead, the content on the page move around in the design to suit the device being used to view the page
A website that use responsive design changes the layout of the website depending on what device is viewing it.
But unlike older solutions,RWD does not use scripts or programming to achieve these changes.
Instead, RWD uses Cascading Style Sheets (CSS) media queries (more about this in Hour 10,"CSS Media Queries") to define fluid grids, variable font sizes, and flexible images.
The media queries design what styles will apply to the design, based on the device being used to view it.