A virtual machine (VM) is an operating system plus one or more apps running in an isolated partition within the computer. Virtual machines may be based on specifications of a hypothetical computer or emulate the computer architecture and functions of a real-world computer.
Understanding the Term
Virtual machines, also known as virtual servers, are full-fledged computers with CPU, memory, and storage, but it is all virtual or simulated, not physical. They have operating systems, files, and applications and do not necessarily live inside a physical server on a one-to-one ratio.
In fact, several virtual machines can live within a single physical server. To the outside world, there is really no difference between a physical server and a virtual server. They both can serve up websites, host applications, and contain data. You can spin up a virtual machine on a desktop PC, on a server, or in the cloud.
VMs are easy to manage and maintain and can run multiple operating system environments on a single physical computer, that way saving physical space, time, and management costs.