Introduction
If you don't quite get the value of Docker, or as a system admin you are can't let go of your SSH console, start with LXC. After that you might (as I have) turn to like what Docker has to offer.
Orchestration
Looking top down, the real power of Docker can only be realized with orchestration technologies. Here are the leading ones, I am just starting to look at,
Kubernetes - Used by Google and they have a free trial to check out.
Apache Mesos - Twitter, Airbnb, Hubspot and Apple run it.
Docker Swarm - Not sure how this fits yet.