Interaction to Next Paint (INP)
A Core Web Vitals metric that measures responsiveness by timing how long a page takes to visually respond to user interactions like clicks, taps, and key presses across the whole visit. It reports the worst representative delay; a good score is 200 milliseconds or less. It replaced First Input Delay in 2024.
Why It Matters
INP reflects how snappy a page feels during real use, not just at load. Slow interactions signal a sluggish experience, and because INP is a ranking signal, poor responsiveness can cost both users and rankings.
Common Mistake
Running heavy JavaScript on the main thread that blocks the browser from responding to input. Large third-party scripts and unoptimized event handlers are frequent causes; break up long tasks to fix it.