Jamstack is an architecture pattern where the front-end is pre-rendered (or rendered on demand at the edge) and assembled at request time from a CMS + APIs. The acronym originally stood for JavaScript + APIs + Markup; in 2026 the term is shorthand for "the modern decoupled web pattern".
Practical shape: a Next.js / Astro / SvelteKit front-end deployed to Vercel / Netlify / Cloudflare, consuming a headless CMS (Contentful, Sanity, Strapi, Sitecore XM Cloud, .NET ABP) over GraphQL or REST. Edge caching + ISR (incremental static regeneration) means page rendering happens once, served thousands of times from the closest POP to the user.
The trade-off vs traditional monolithic CMS: more moving parts at the start, but cleaner separation of editorial concerns from front-end engineering, and materially better delivered performance.