Responsive web design is understandably very popular with nearly one third of all website views in 2014 coming from a smart phone. This means every website needs to be responsive so as to provide an optimal viewing experience across radically different devices and screen sizes from mobile phones, through various sized tablets, laptops and super high definition HD monitors. Screen sizes will always be changing so it is important to design sites that can adapt to any screen size and still look and work well.
According to Google responsive web design should serve the same HTML content to all devices, so that all your visitors see the same information. It is how this information is styled across different screen sizes that is important but this also means that creating a separate theme or template for mobile, tablet and desktop is also not a good option as it means that you will more than likely be serving different content.
The site uses four breakpoints to snap to four different layouts, changing the number of columns as screens get larger; making the most of the space on different devices.