Server Side Rendering (SSR) is a technique in web development where a web page is generated and rendered directly from the server, rather than in the user's browser. This means that when a user visits a website, the server sends a fully rendered page to the browser, and all the browser has to do is display it.

SSR is important in the modern web for a couple of reasons.

• It can improve the performance of a website as it reduces the amount of work that the browser needs to do. This means faster load times and a better user experience.
• It's beneficial for Search Engine Optimization (SEO). Web crawlers can more easily index server-rendered content, which can help a website's visibility in search engine results.

Server Components are a new paradigm introduced in React 18, and Next.js 13+ supports Server Components through the app directory.