So, what is Docker?
Well, Docker is like a virtual machine (VM), but it's not. In a traditional VM setup, you would take a machine, install an operating system on that machine, and then install a hypervisor, such as VirtualBox (for more information, visit https://www.virtualbox.org) or VMware (to know more about VMware, check out http://www.vmware.com). You could then create a VM image on the hypervisor, which pretends to be a computer. This image would have its own BIOS and emulated hardware. You would then install an OS on this image. This is generally referred to as the guest OS. Once this is done, you would boot up the guest OS and then treat it like any other computer.
If you want to isolate your applications, you can create multiple guest OSes, but this can be costly:
Docker is slightly different. It is a program that you install on the host...