UI Design
Optimistic Update
An optimistic update is when the interface shows the result of an action immediately, before the server has confirmed it succeeded. It assumes the request will work and updates the screen right away.
Why it matters
Waiting for a server response on every action makes an app feel slow. Optimistic updates make interactions feel instant, which is a big part of why some apps feel smooth and others feel sluggish.
In depth
The pattern trades certainty for speed, so it requires a graceful rollback when the request fails — reverting the change and ideally telling the person what happened. It works best for low-risk, reversible actions like liking or reordering, and is riskier for actions where a silent failure would mislead someone. Pair it with clear feedback so a reverted state never feels like a glitch.
Real-world example
When you like a post, the heart fills in instantly even though the request is still traveling to the server. If the request fails, the app quietly undoes the change.
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