Server-side rendering (SSR) is a technique where web pages are rendered on the server and sent as fully formed HTML to the client. This can greatly improve SEO, reduce the time to first meaningful paint, and enable prefetching and caching for better performance.

**When to Use SSR:**
– SEO is a priority, as search engines can index server-rendered content more easily.
– Fast initial page load is needed, especially for public-facing content sites.
– Prefetching data and caching entire HTML responses can boost speed and reliability.

**When Not to Use SSR:**
– Internal dashboards, SPAs, or applications behind authentication, where SEO and public discoverability are not concerns.
– Highly interactive interfaces where constant server round-trips add unnecessary complexity.

Choosing whether to implement SSR depends on your application’s goals and audience. SSR can provide significant benefits for the right use cases.