Docker is an open platform that helps to distribute applications and complete systems. In some ways, it is similar to a virtual machine, but it is much faster and more flexible; see https://www.docker.com or https://dockerproject.org for more information.
In order to install it in Ubuntu, you only have to run the following:
$ sudo apt-get install docker.io
Docker images are like virtual machines or systems already set up. There are servers that provide images like this, so the users only have to download them. The main server is Docker hub, found at https://hub.docker.com. There, it is possible to search for Docker images for different systems and configurations. ...