Definition
Also written: CWV, LCP, CLS, INP
Core Web Vitals are Google’s three user-experience metrics: Largest Contentful Paint (loading), Interaction to Next Paint (responsiveness) and Cumulative Layout Shift (visual stability). They are a confirmed ranking signal, and independent analysis indicates they act as a tie-breaker among comparable pages rather than a primary driver.
The gap between lab and field data causes most confusion. A Lighthouse score is a simulation on modelled hardware and network conditions; ranking uses field data from real visitors.
INP replaced First Input Delay in 2024 and is stricter — it measures the full interaction-to-paint duration rather than input delay alone.
The usual error
Where this goes wrong in practice
Optimising a lab score while field data stays poor. They diverge routinely, and only one of them is used for ranking.
Related terms
Largest Contentful Paint (LCP)
Largest Contentful Paint measures when the largest visible element in the viewport finishes rendering — usually a hero image, a video poster or a large text block. Google’s threshold for "good" is 2.5 seconds at the 75th percentile of real visits.
DefinitionSearch engine optimization (SEO)
Search engine optimization is the practice of making a site easier for search engines to crawl, index, understand and rank, so that pages appear for queries the business can actually serve. It covers technical access, information architecture, content quality, internal linking, authority signals and the measurement that tells you which of those moved.
DefinitionSearch experience optimization (SXO)
Search experience optimization joins ranking work to what happens after the click — page experience, clarity, task completion and conversion. It is the most stable term in the acronym cluster because it describes a genuine scope difference rather than a new surface, and it predates the generative-AI wave.
Definition