It’s a design philosophy that puts the design of the mobile experience front and center in the process, rather than as an afterthought.
When we say we’re designing “mobile first” we’re really saying that we’re thinking about how the application or website will function on the mobile device as a primary focus of our designs.
We’re paring down the features of any experience to it’s primary function, and making sure that is easy to do on mobile. Then we add features for tablets and desktop.
Back in the day when mobile devices were new, the last thing designers thought about (literally) was how to translate their beautiful websites into the tiny mobile screen. It was an afterthought, and usually was handed over to a specialist who just designed for mobile experiences.
But those days are long gone. Today, more people access websites and applications from their mobile devices than from their desktops or laptops.
And all designers are expected to be designing for all screen sizes.
When designing for mobile was an afterthought, the approach was to take the existing website and remove as much as possible until it could fit on a smart phone-sized screen.
We called this “graceful degradation.” But really, there was nothing graceful about it.
What was often left was a series of list menus and very little content. It was a terrible user experience.
The approach I use and recommend is to first understand the primary use of your application. What does the main persona want to do when they land on your website? That is the core functionality — the one thing that must always be working, and working well, at any screen size.
Then design a mobile experience for that core function.
Once you’ve designed the mobile flows, interface and IxD for that core function, you can work on the tablet and desktop versions. With bigger screens, you’ve got more real estate to add more features. So go ahead and add them.
The point is, you’ll have a better mobile experience for the majority of users who access your website from a mobile device if you design specifically for that device.
Progressive enhancement over graceful degradation.