Docker images are slightly different from containers. That is, the image is the stored copy of the container. Docker images are stored in what is commonly referred to as a registry. In the context of Docker, the registry acts similar to a source control solution in many ways. That source control solution is mirrored in many ways to Git. Docker registries parallel Git in many ways; the most obvious is the ability to have a distributed set of registries. Confused yet? Let's take a look at the following diagram:
From the preceding illustration, we can see that the Docker registry is a remote location that stores Docker images. Docker images then reside in a local registry (local to the developer) where they can manipulate and store changes made to the various containers stored within the Docker registry. When a set of changes has been deemed complete, the developer has the option to push the image(s) to the remote registry and communicate their changes.