“Docker is an open platform for building, shipping and running distributed applications. It gives programmers, development teams and operations engineers the common toolbox they need to take advantage of the distributed and networked nature of modern applications.” — Docker website
Docker is becoming an important tool for HEP scientists to use many different computing architectures. The tutorial on their website is well written and easy to follow. Go to the website and click ‘Get Started with Docker’. You can start playing with it right away.