A virtual machine is a software computer that acts like a physical computer, and runs on an operating system and applications. It is a software application of a machine (a computer) that executes programs similar to a physical machine.
VM comprises of a set of specifications and configuration files, backed by the physical resources of a host. Each of the virtual machine comprises of virtual devices that deliver the same functionality as a physical hardware and have additional benefits in terms of security, portability and manageability.
A virtual machine consists of several types of files that can be stored on a supported storage device. The key files that a virtual machine comprises of are -configuration file, NVRAM setting file, virtual disk file and the log file. You can configure the virtual machine settings through the Vsphere Web Client or the vSphere Client. There is no requirement to amend the key files.
Virtual machines can be further segregated into two major classifications as per their usage and the degree of correspondence to any real machine. These are System virtual machine and Process virtual machine.