ISR: A flexible way to cache dynamic content

Incremental Static Regeneration (ISR) is a caching strategy that combines the benefits of static site generation and server-side rendering to provide users with dynamic content at cached speeds. ISR allows for fast serving of edge-cached static content while updating data in the background, selective regeneration of specific pages without rebuilding the entire site, on-demand invalidation, and guaranteed cache durability. It pairs best with hybrid rendering frameworks that allow for some content to be prerendered and some served per request. ISR can act as a full replacement for HTTP caching at the edge, allowing developers to focus on which pieces of their app would benefit from caching. Several popular frameworks currently support ISR, including Next.js, SvelteKit, and Astro.