what's the liquid glass ui?

Liquid Glass is a new design material introduced by Apple at WWDC 2025. It combines the optical qualities of glass with a responsive fluidity, creating a new level of depth and vitality in user interfaces. Liquid Glass is designed to refract content from below, reflect light from around it, and have responsive lensing along its edges. This makes the UI feel fluid and alive, as if the physical glass of the device is the UI itself. It is more than just a visual enhancement; interactivity is at the core of its design, with features like specular highlights and refraction that visually lift controls while maintaining a close relationship to the content beneath.

Liquid Glass is used across Apple platforms to create a seamless and harmonious user experience. It adapts to light and dark environments, morphs dynamically when more options are needed, and enhances navigation and controls by bringing clarity and vitality to the user interface. This new design is supported by Apple's UI frameworks, including SwiftUI, UIKit, and AppKit, allowing developers to integrate Liquid Glass into their apps with ease.