Core Web Vitals are three metrics. LCP measures when the largest element appears (good is under 2.5 seconds). INP measures how fast the page responds to a click (good is under 200 ms). CLS measures how much the layout shifts while loading (good is under 0.1).
Why track them
Google uses them as one of its ranking signals. What they measure matters more, though: a slow, unstable page loses visitors before they read the first sentence.
Where they usually break
Large uncompressed images, heavy page builders, dozens of plugins and third-party scripts loading at once. Fixing it is often cheaper than it looks when done systematically.
