Core Web Vitals are Google's standardized performance metrics that quantify real user experience. The three current metrics are Largest Contentful Paint (LCP, should be under 2.5 seconds), Interaction to Next Paint (INP, should be under 200ms), and Cumulative Layout Shift (CLS, should be under 0.1). LCP measures how quickly your main content loads, INP tracks how fast your page responds to user interactions like clicks and taps, and CLS measures how much your page layout jumps around while loading. They matter for three concrete reasons. First, they're confirmed ranking signals—Google uses them in search rankings, though the weight varies by query and competition level. Second, they correlate directly with business metrics. We've seen conversion rate drops of 15-25% when LCP crosses 3 seconds, and bounce rates climb sharply when CLS causes users to tap the wrong element. Third, they're measured from real Chrome users through the Chrome User Experience Report, so you can't game them with lab-only optimizations. The shift from First Input Delay to INP in March 2024 raised the bar significantly. INP measures all interactions throughout the page lifecycle, not just the first one, which means heavy JavaScript frameworks and third-party scripts now hurt you more than before. Common culprits we fix: - Unoptimized images causing slow LCP (WebP conversion and lazy loading) - Render-blocking CSS and JavaScript delaying interactivity - Missing size attributes on images and embeds causing layout shifts - Third-party ads and chat widgets loading without proper containers At Ottawa SEO, we prioritize Core Web Vitals fixes based on traffic value—homepage and high-converting landing pages first, blog archives later. We track field data through Search Console and PageSpeed Insights, not just lab scores. A site passing in Lighthouse but failing in field data still has a ranking problem. For competitive niches in Toronto or Montreal markets, good Core Web Vitals won't guarantee top rankings, but poor ones will actively hold you back from positions you'd otherwise claim.