Over the past several years, people have overwhelmingly transitioned toward using their mobile devices to view websites more often than using their computers. As this trend began, many sites responded by creating separate, slimmed-down versions of their websites to be viewed on mobile devices. This strategy caused mobile sites to be clunky and slow.
Alternatively, many weren’t even taking mobile visits into account, so their visitors were left to scroll endlessly across a website designed to fit a desktop to find the content they were looking for.
Today, we have a wonderful thing called “responsive design.” This means building websites that automatically adjust themselves based on the screen they’re being displayed on. This is incredibly beneficial for a number of reasons, including mobile load time. Responsive sites load faster than ones with dedicated mobile sites because they don't involve any URL redirects.
In tandem with the development of responsive design has been the emergence of ‘mobile first design.’ This strategy is pretty much exactly what it sounds like — beginning the entire design process with the mobile display.
This strategy has become overwhelmingly popular among website designers, and for good reason. Not only does it ensure a pleasurable experience for mobile users, it makes life easier as a designer as well.
First, mobile-first design means getting the most difficult tasks finished right at the beginning. Once the mobile design has been sorted out, it will make designing for other devices much simpler. Mobile screens are the smallest of all devices, so their design includes only the essentials - allowing them to serve as the baseline for all of your UX.
Mobile first design forces you to focus on content, and therefore focus on your user. You only include the content that your users are looking for, avoiding the fluff you might otherwise add. Everything on your site is vital.
As you move through the design process, you can make additions to appear on larger-screened devices, but doing so in a way that makes your content even more robust will mean building an incredible website no matter how your users are viewing it.