Before we start using Docker, you obviously need to install it. There are several installation channels to choose from. For many Linux distributions, there are packages available in their package manager. For Windows and macOS, you need to go to the Docker website and download the installer. This is actually the preferred one as the versions available from the package managers may not be up to date.
There are several graphical interfaces to manage Docker, but we'll keep it simple and just use the command-line interface. This gives you greater control and you get to know more of the internals of how everything is glued together.
So, let's open a console and type docker info to check whether everything is correct: