Understand and apply the Core Web Vitals good/needs-improvement/poor thresholds for LCP, INP, and CLS, and interpret the p75 assessment rule

Steps

1. Learn the three current Core Web Vitals metrics: Largest Contentful Paint (LCP) good threshold is under 2.5s, Interaction to Next Paint (INP) good threshold is under 200ms, Cumulative Layout Shift (CLS) good threshold is under 0.1
2. Understand the p75 rule: a page passes a metric only if at least 75% of real-user sessions are in the 'good' range — the 75th percentile value must be at or below the good threshold
3. Retrieve p75 values from the CrUX API or Search Console Core Web Vitals report, not from Lighthouse lab scores which measure a single synthetic run
4. When a URL has insufficient real-user data, the CrUX API falls back to URL-group level, then to origin level — identify which granularity is being returned via the 'record.key' in the API response
5. Use the Search Console Core Web Vitals report to identify which URL groups (grouped by similar URL patterns) are failing, then investigate representative URLs with PageSpeed Insights
6. Track pass rate trends over time using the CrUX BigQuery dataset (bigquery-public-data.chrome-ux-report) rather than spot checks to understand regressions