The Bakery is a an Amazon Machine Image (AMI) factory. Whenever your code changes, the Bakery will take those changes and build a new image from it. That image can be deployed to 1 or 1000s of EC2 instances. Why? Some (e.g. Netflix) like to build fully configured images containing the latest code, and use the same image for staging and promote it to production after testing. Others like to build an image containing just the dependencies for running their service, and get the code on boot. You could even build an AMI containing a Docker image, so that when you launch 100 instances, they aren't all downloading the same Docker image on boot. The point is, it is a simple little factory, and how you want to use it is up to you.