Rendering

Rendering is the process by which search engines execute JavaScript and CSS to understand the final visual appearance and functionality of web pages. Modern search engines like Google use headless browsers (based on Chrome) to render pages similar to how users see them. This is critical for JavaScript-heavy sites (SPAs, React, Angular) where content may be loaded dynamically. Poor rendering can lead to content not being indexed or understood by search engines. Optimization includes server-side rendering (SSR), dynamic rendering for bots, minimizing render-blocking resources, and testing with Google's URL Inspection Tool. Rendering performance also impacts Core Web Vitals, particularly First Contentful Paint (FCP) and Largest Contentful Paint (LCP).