Docker is kind of like a virtual machine, except without all the overhead of the operating system so you have a much smaller package. It also uses Linux contain

Docker is kind of like a virtual machine, except without all the overhead of the operating system so you have a much smaller package. It also uses Linux containers ( http://en.wikipedia.org/wiki/LXC http://en.wikipedia.org/wiki/LXC) to help with this process. The overall idea is that I can make an app, use Docker to control things like versions of 3rd party apps that your app relies on. So for a web app I can include the version of MySQL, PHP, Ruby etc that I want, and then distribute a "dockerized" version of the app. Now when I distribute for testing or to other servers I don't need to worry about versions. It just works. At least that's what I gather from reading their site last weekend. I plan to start using it for one of our projects soon.