Each command in the Dockerfile potentially creates a new layer in the image. This allows container deployment to be very efficient. For example, if we subsequently change some code in our service and rebuild the container, this will result in a very thin layer being created that represents the delta between the last image and this one.

This means that if our target deployment environment has all of the previous layers, deployment of a new version of a container may only require a new layer of a few kilobytes or less.

Let's explore Docker layers.