What is Docker?

The Docker (https://www.docker.com/) project is a container platform, which lets you run your applications in isolated environments. Using the Linux feature called cgroups (https://en.wikipedia.org/wiki/Cgroups), Docker creates isolated environments called containers that run on Linux without a VM. On macOS and Windows, installing Docker will create a lightweight VM for you to run containers in, although this is a seamless process. This means that macOS, Windows, and Linux users can all develop container-based applications without worrying about any interoperability trouble and deploy them to a Linux server where they will run natively.

Today, Docker is almost synonymous with containers, but there are other container runtimes, such as CRI-O (https://cri-o.io/), and historical projects such as rkt and CoreOS that, together with Docker, helped shape the standardized ecosystem that we have today.

Because containers do not rely on emulation when running on...