What is the JAM Stack
Markup: Templated markup should be built at deployment, usually using a site generator for content sites, or a build tool for web apps like Gatsby.js or Webpack.
Advantages of JAMstack
Better Performance, pages are generated at deploy time instead of traditional build on the fly.
Higher Security, with server-side processes abstracted into microservice APIs, surface areas for attacks are greatly reduced.
Cheaper and Easier Scaling, static content can be placed on a CDN making it very easy to dynamically scale it.
Better Development Experience, Loose coupling and separation of controls allow for better development and debugging.
JAMstack vs Traditional
In traditional workflow, building and hosting are coupled. When a user request a page, the page is procesed and served with a long series of interaction between the back-end and the database. With the JAMstack building and hosting are decoupled, when a user request a page, the page is already build and it is directly served from the CDN. Updates to the traditional way are with platforms like WordPress or Drupal, the JAMstack content updates are through Git or a static site CMS.