SSR generates HTML on the server for each request. The browser receives complete markup.
How it works:
Request hits server
Server fetches data and renders HTML
Complete HTML sent to browser
JavaScript hydrates for interactivity
Pros: Fast first contentful paint, good SEO, works without JavaScript.
Cons: Server load per request, slower time to interactive, complex caching.
Use when: Content changes frequently and SEO matters. News sites, e-commerce product pages.