Earlier this year, pictures of a new Windows look leaked. Codenamed Project Neon, the new look builds on Microsoft Design Language 2(MDL2), the styling used in Windows 10 right now, Neon adds elements of translucency and animation. Neon has now been officially announced, it is now called the Microsoft Fluent Design System.
New "design system" will span everything from phones to virtual reality.
The awkward MDL2 name exists because the original codename for the geometric, text-centric style was under a trademark dispute. That look was internally named Metro UI. Microsoft had to stop using the Metro name after pushback from a German supermarket chain. It wasn't until a couple of months after dropping "Metro" that a new name, "Microsoft Design Language", was chosen.
This time, microsoft seems to have recognized the importance of having an official name for the style that it can talk about and describe. And to meet these needs, Microsoft Fluent Design System was born.
One of the biggest issues with Metro was that Microsoft did not provide guidance to developers on how to build their interfaces. First-party applications are important, as many developers mine those applications for useful interface concepts and ideas. The Metro apps that the company shipped tended to all be quite simple, offering little insight into how applications with complex interfaces should be designed.
A few apps available to Insider Builds of Windows 10 have already started to pick up Fluent Design elements. For example, The Groove App now has some Transparency effects and this will continue until the next Major Windows Update, the Fall Creators Update.
The move to Fluent will not happen within the Fall Creators Update timeframe, however; it's a longer-term project. Microsoft says that the transition to and adoption of Fluent will take longer than the six-month interval between each Windows Release.