Ever since I discovered Docker, I’ve been a fan. Trying to explain Docker to the un-initiated is also fun. I describe it like so:
Docker is like a Lunchable (or bento box). The container of said Lunchable is Docker and the VM it controls. Every section inside the container is each of the apps it runs.
I try to tell folks that you use a Virtual Machine if you need to control an entirely specific environment. You use Docker if your interest is just with apps. In this day and age, trying to maintain a fleet of systems or virtual machines can be daunting.