Core Web Vitals
Core Web Vitals are a set of metrics used to understand how a website behaves from a user’s perspective.
This collection groups Largest Contentful Paint, Interaction to Next Paint, and Cumulative Layout Shift with the hosting, caching, and front-end work that actually moves those numbers — so a lab score is never treated as the whole story.
Terms
Core Web Vitals (CWV)
A set of metrics used to measure how users experience a website’s performance.
Cumulative Layout Shift (CLS)
Measures how much visible content moves unexpectedly while a page loads or updates.
Interaction to Next Paint (INP)
Measures how long it takes for a page to visibly respond after a user clicks, taps, or types. It reflects how responsive the page feels during use.
Largest Contentful Paint (LCP)
Measures how long it takes for the main content of a page to become visible.
System Behaviour
How a website performs as a whole, based on how its components interact across real users, conditions, and usage.
Time to First Byte (TTFB)
Measures how long it takes for a server to begin responding after a page request.