Shimmer
An animated gradient that sweeps across a skeleton placeholder to signal that content is loading.
Where a static skeleton uses flat gray shapes, shimmer adds a moving highlight that travels across them. The motion reassures the user that the app is working rather than frozen. Typically implemented with a CSS linear-gradient and a `background-position` animation.
Also called
shimmer effectanimated skeleton
When to use
- Loads expected to take more than ~500ms where a static skeleton would feel stuck
- Feeds and lists where many skeleton items animate together
When not to use
- Very short loads — the animation appears and disappears too fast to read
- Anywhere reduced-motion preferences are set (provide a static fallback)
Related
Source
Facebook is widely credited with popularizing the effect around 2017 in its mobile apps.