Understanding Virtual Machines
It is common for IT professionals to refer to a Windows or Linux system running on an ESXi host as a virtual machine (VM). Strictly speaking, this term is not 100% accurate. Just as a physical machine is bare-metal hardware before the installation of an operating system, a VM is an empty shell before the installation of a guest operating system (the term “guest operating system” is used to denote an operating system instance installed into a VM). From an everyday usage perspective, though, you can go on calling the Windows or Linux system a VM. Any references you see to “guest operating system” (or “guest OS”) are references to instances of Windows, Linux, or Solaris—or any other supported operating system—installed in a VM.
If a VM is not an instance of a guest OS running on a hypervisor, then what is a VM? The answer to that question depends on your perspective. Are you “inside” the...