ISR combines SSG's performance with SSR's freshness. Pages regenerate in the background.
How it works:
Initial build generates static pages
Pages served from cache
After revalidation period, next request triggers background regeneration
New version replaces old once ready
Configuration:
export async function getStaticProps() {
return { props: {...}, revalidate: 60 }; // Regenerate every 60s
}
Use when: Content updates periodically but doesn't need real-time freshness.