At WWDC in June 2020, Apple unveiled macOS Big Sur — pushing the 'vibrancy' it had used since 2014 across the whole system. Window backgrounds blur, the Dock turns translucent, Control Center floats above the wallpaper. The same year Microsoft adopted 'Mica' and 'Acrylic' materials throughout Windows 11. In 2025 Apple officially named it 'Liquid Glass' — the system aesthetic's official name from iOS 26 on.

It solved a problem Flat Design didn't: when everything is pure colour, the sense of hierarchy disappears — you can't tell which panel floats on top and which sits beneath. Glassmorphism uses the fact that it 'lets the colour below show through' to visualize z-index.

The key to doing it well is 'there must be something underneath to show through': glass on a pure-white base just looks like a pale grey block. It needs a saturated, layered, colourful background (wallpaper, video, gradient) to refract. And you can't stack glass on glass on glass — past three layers you can't tell which is in front.

Today its strongest uses: the system OS layer (Windows, macOS, iOS), video-player overlay UI (YouTube full-screen controls), and dashboard floating panels. Using it on a product's main screen actually disrupts reading — it's a supporting actor, not the lead.