SSG (Static Site Generation) is a rendering strategy where pages are pre-rendered to HTML at build time and served as static files from a CDN, providing maximum performance and resilience but no per-request freshness.
SSG works perfectly for content that doesn't change frequently — marketing pages, documentation, blog posts. It scales horizontally trivially because the rendered HTML is just files on a CDN.
For ecommerce, pure SSG hits limits on dynamic content (cart, account, personalized recommendations, real-time inventory). Modern ecommerce typically combines SSG-cached shells with dynamic islands for personalized content — the pattern PPR formalizes in Next.js 16.
Build-time SSG also struggles with very large catalogs. A 100,000-SKU site that statically generates every PDP at build time may take hours to build, blocking deploys. ISR or Cache Components + on-demand revalidation are usually better at scale.