Suggest an editImprove this articleRefine the answer for “What is FID (First Input Delay)?”. Your changes go to moderation before they’re published.Approval requiredContentWhat you’re changing🇺🇸EN🇺🇦UAPreviewTitle (EN)Short answer (EN)**FID (First Input Delay)** is a metric that measures how quickly a site responds to the user's first action. **Key point:** FID matters for interactivity - fast loading is one thing, and a fast reaction to actions is another.Shown above the full answer for quick recall.Answer (EN)Image**FID (First Input Delay)** is a metric that measures **how quickly a site responds to the user's first action**. --- ### What counts as an "action": - clicking a button; - clicking a link; - typing into a form field. --- ### What is measured: **The delay between the moment the user pressed something and when the browser started processing it.** Not when the result appeared, but when the site *started* reacting. --- ### Why this matters: If a person clicks and nothing happens, they perceive the site as "sluggish." Even if everything is visually loaded. --- ### Norms: - **up to 100 ms** - good; - **100-300 ms** - acceptable; - **more than 300 ms** - causes irritation. --- FID matters for interactivity. Fast loading is one thing, and a fast reaction to actions is something else entirely.For the reviewerNote to the moderator (optional)Visible only to the moderator. Helps review go faster.