---
title: "Incremental Static Regeneration (ISR) — Definition & Engineering Context"
description: "Incremental Static Regeneration (ISR) is a Next.js rendering pattern that allows developers to update static pages in the background after site deployment without rebuilding the entire website."
canonical: https://erpstack.io/glossary/isr
markdown_url: https://erpstack.io/glossary/isr.md
publisher: ERPStack
---

# Incremental Static Regeneration (ISR)

> **Definition:** Incremental Static Regeneration (ISR) is a Next.js rendering pattern that allows developers to update static pages in the background after site deployment without rebuilding the entire website.

## In depth

ISR combines the speed of static site generation (SSG) with the flexibility of server-side rendering (SSR). Pages are pre-rendered at build time. When a request is received, the edge serves the cached static page. In the background, Next.js revalidates the data. If the database changed, it regenerates the static page and updates the cache without downtime.

## How ERPStack applies this

We implement on-demand ISR across all ERPStack programmatic pages. When a case study or term changes in the database, our webhook invalidates the page cache in under 300ms.

## Related reading

- [Edge Caching / CDN](https://erpstack.io/glossary/edge-caching)
- [Next.js SaaS Starter Boilerplate](https://erpstack.io/glossary/saas-boilerplate)