Server-Side Rendering (SSR) is a web development technique where web pages are generated on the server rather than in the browser. When a user requests a page, the server processes the request, creates the HTML content, and sends it to the user's browser. This allows for faster initial loading times and better performance, especially for users with slower internet connections. SSR is beneficial for Search Engine Optimization (SEO) because search engines can easily crawl and index the fully rendered pages. Additionally, it improves the user experience by displaying content quickly, reducing the time users spend waiting for a page to load.