Flat design is minimal that's free of bezels, most gradients, and drop shadows to create a 2D look with no added effects. Minimalism and efficiency is now king, especially with a focus on typography and content. Flat design is all the rage in web design, but it's creeping up in all aspects of graphic design.
Flat Design has been around for a while, but didn't really get too much buzz until Apple changed the iPhone and iPad's entire interface to flat with the introduction of iOS 7 in 2013. That's not to say that Apple was the first, or even the best to implement flat design.
The only reason it became a big deal when Apple change their design is because the change was so drastic from what Apple users were used to using. Apple designs were previously skeuomorphic, which means the digital items looked like their real life counterparts. All of a sudden the yellow sunflower with cloud-filled sky background wasn't the app for pictures. Now it's a multicolored object that somewhat resembles a flower and looks nothing like a picture.
Initially there was some backlash from users who liked the way iOS 6 looked, especially since they were unable to simply change back the look of the device to the more "real" look. The new flat design was part of the iOS 7 update, and you could either update to the new flat look and get cool new features, or be stuck with what would become outdated technology.
Apple was preceded by Microsoft's media center and it's Zune. Microsoft introduced a typography based design language called Metro. The language was unveiled with the Windows Phone 7 and is still prevalent in Windows 8.
Skeuomorphism can date back to Apple's first consumer GUI (Graphical User Interface) back in 1984. Apple named the interface a "desktop" and filled it with icons that looked like folders and pieces of paper. The computer was still foreign concept to users, so skeuomophism was a necessary tool that visually connected old familiar objects to what were new and confusing ones.
While skeuomorphism may have had its place back when computers were new, in the modern age there are a lot of issues with skeuomorphic design. Skeuomorphic techniques add extra detail and design that don't support functionality.Visual trickery is used to make one thing look like another and digital elements are designed to look like something from the physical world. Skeuomorphic designs use textures, shadows, and gradients to make digital objects look like their "real" counterparts.
In contrast, flat design is considered to be simple and efficient. It often incorporates straight lines and squared corners with high color contrasts. Sometimes shadows will be used, but more for visual interest instead of to establish depth. Flat design provides visual clarity by losing extraneous styling.
Instead of wasting time getting gradients and shadows just right for something to look "real" a designer can spend time making their product just look good and be functional. The content becomes the center of the design.
Often, flat design is filled with bright colors and fun typography and can be described as fresh, clear, simple, and light.
Perhaps the real culprit behind the switch to flat design is the emergence of responsive design and mobile design? Textures, gradients, and shadows usually don't translate well on smaller devices. Maybe skeuomorphism was truly abandoned because of the popularity of mobile devices. Designers want their mobile design to look as similar as possible to the desktop version for brand cohesiveness.
Designers don't want to distract the user on a smaller screen, and a bunch of over stylized icons can make it difficult to navigate a site.
Will flat design stick around forever? Probably not. Eventually the design will most likely revert back to more realistic looks, just like what's happened in the art world. People may forget that things used to look "real" and will suddenly crave it again, almost as if it's a new concept.