Lighthouse, an open-source tool developed by Google, is instrumental in evaluating website performance through metrics like Core Web Vitals, which influence search rankings. The tool assesses websites based on various criteria, including accessibility and SEO best practices, and can be run via Google PageSpeed Insights, Chrome DevTools, or command line. Key metrics include Largest Contentful Paint (LCP), First Input Delay (FID), and Cumulative Layout Shift (CLS), which measure loading performance, interactivity, and visual stability, respectively. To enhance Lighthouse scores, website optimization strategies include image optimization, reducing page bloat, following progressive web app standards, using lazy loading, minimizing custom fonts, and removing unnecessary features. For Gatsby-powered websites, specific techniques such as using the Gatsby Image Plugin, trimming bloated bundles, delaying script loads, and possibly using Preact instead of React are recommended for improving performance. The document underscores the importance of quality content for search rankings and offers additional resources for further exploration of website optimization.