flat design

With regard to user interfaces, a flat design rejects the 3D-looking sculpted, shadowed and translucent window borders and icons that were so popular starting with the personal computer explosion and lasting well into the 21st century.

A flat design is essentially two dimensional. Starting in 2012, Windows 8 switched to the flat design, followed by Apple and Android. Everything runs in cycles. In 2017, Microsoft introduced a new UI style that moves away from the entirely flat look in Windows 8 and 10 (see Microsoft Fluent Design System and Metro interface). See iOS 7, Material Design, skeuomorph and user interface.

Old Vs. New

The Windows 7 application buttons (top) were shaded, while the same buttons in the next versions of Windows are displayed without any attempt at making them appear 3-dimensional.

Forget Old Fashioned

In 2013, the user interface became flat in Apple's iOS 7 operating system. See iOS 7 and skeuomorph.