The discipline of making JavaScript-rendered pages discoverable and indexable by search engines. Google's crawler can execute JavaScript, but in two passes: first the raw HTML is indexed, then later (sometimes days later) the rendered DOM is processed. Common pitfalls include client-side-rendered content that returns blank HTML, links that only appear after JS execution, and lazy-loaded content that never triggers without user interaction. Solutions include server-side rendering (SSR), static site generation (SSG), and selective hydration. Google deprecated dynamic rendering as a recommendation in 2024 in favour of SSR/SSG.