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Frontend Glossary

Frontend engineering · Rendering

Incremental Static Regeneration

Also called: ISR, Regenerate static pages, On-demand revalidation

Pages are still generated and cached as static files, but can regenerate in the background after they expire—static speed with fresher content.

In detail

Pure SSG needs a full rebuild to update; pure SSR computes every request. ISR is a middle path: serve static, set a revalidate time or on-demand trigger, and regenerate in the background after expiry so later users see the new version.

It fits content sites, docs, and catalogs that tolerate slight delay. Be careful with auth and personalization—don't force ISR on per-user data.

Together with a CDN, "why is it stale?" might be the ISR window or an edge cache that wasn't purged.

Developer info
Term ID
eng-isr
DOM selectors
No DOM cues. This concept isn't detected directly on a page.
Priority
1 · when several match at the same level, the higher priority wins
Version
v1 · updated Oct 5, 2026