Responsive website design and development means creating a website that adapts (i.e. responds) to the size of the screen you’re viewing it on without redirecting to a different file or loading separate code.

A responsive website design works on small mobile-phone screens, large desktop computer monitor screens, and every screen size in between and beyond. Theoretically, responsive websites are designed and developed to work everywhere for everyone on any device at all times because it’s good for business. Most all modern websites and WordPress themes are already responsive, so it’s actually become difficult to build or buy a website that is not.

Responsive Website Design is Mobile-Friendly

Having a responsive website means your website is mobile-friendly. Sometimes you may even hear responsive website design referred to as mobile-friendly or mobile-responsive website design. If we’re splitting hairs there are varying degrees of difference between the terms responsive, mobile-friendly, and mobile-first. Depending on how your website is developed, mobile-friendly doesn’t necessarily mean mobile-first and mobile-first doesn’t necessarily mean mobile-friendly, but both terms can live under the overarching umbrella of responsive website design. However, for all intents and purposes most people mean to imply the same idea — that your website works and looks good on any screen size — when referring to a website as mobile-friendly, mobile-first, responsive, and mobile-responsive.

How to Test a Website’s Responsiveness

Testing a website’s responsivity — its responsiveness — is as easy as changing the size of your web browser window. View a website in any desktop web browser and resize it by changing its width and/or height to see how it displays at various screen sizes. Observe how the website’s layout and on-screen elements change, move, adjust, and adapt when your viewport is set to different widths and heights.

Responsive Websites Adapt at Common Breakpoints

How responsive a website’s design is depends on how the website was coded. Most modern website designs account for at least a mobile, tablet, and larger-sized screen width with responsive breakpoints at approximate screen widths of 320px–578px for smaller screen sizes, 768px for medium screen sizes such as tablets being viewed in portrait mode, 960px-1024px for tablets in landscape mode and smaller laptops, and anything larger for typical desktop computer monitors or screen sizes of higher resolutions.