Passing Core Web Vitals means hitting three thresholds on at least 75% of real user page loads: Largest Contentful Paint under 2.5 seconds, First Input Delay under 100 milliseconds (or Interaction to Next Paint under 200ms as of March 2024), and Cumulative Layout Shift under 0.1. Google measures these from Chrome users who opted into usage statistics, not from lab tools alone. For LCP, the biggest wins come from optimizing your hero image or largest above-fold element. Use modern formats like WebP or AVIF, size images appropriately, implement lazy loading below the fold, and preload critical resources. If your LCP element is text, ensure your web fonts load fast with font-display swap and preconnect to font CDNs. Server response time matters too—aim for TTFB under 600ms by using a quality host, enabling caching, and minimizing server-side processing. FID and INP both measure responsiveness. Reduce JavaScript execution time by code-splitting, deferring non-critical scripts, and removing unused libraries. Third-party scripts like analytics and chat widgets are common culprits—load them asynchronously or delay them until after user interaction. Break up long tasks so the browser can respond to clicks and taps quickly. CLS happens when elements shift after initial render. Reserve space for images and ads with explicit width and height attributes, avoid inserting content above existing content unless triggered by user action, and ensure custom fonts don't cause text reflow by using font-display optional or preloading fonts. Dynamic banners and cookie notices are frequent offenders. At Ottawa SEO, we test with PageSpeed Insights for field data and Lighthouse for lab conditions, but we prioritize the field data from Search Console's Core Web Vitals report because that reflects real user experience. We've seen sites jump from "Needs Improvement" to "Good" just by compressing images and moving chat widgets to load on scroll. The assessment is binary—either 75% of your page loads pass all three metrics or you fail—so fixing the worst offenders gives you the fastest ROI.