A quick note on Docker image repositories
We’ve been working quite a bit with the nginx image in this chapter. But where exactly is this image coming from? By default, Docker attempts to download images from Docker Hub (https://hub.docker.com/), which is a central repository of public Docker images. Docker Hub works like a Linux package repository, which contains uploaded Docker images ready for you to use. Most popular server software can be found there and can be downloaded and used as easily as you just saw with nginx.
Not all applications are public, however, and it’s normal to use private repositories to store Docker images. There is an ever-changing list of Docker image repository providers, so we won’t list them here, but it’s enough to understand that they all work the same way as Docker Hub.
