What is virtual machine and how does it work?

Virtual Matchine

In the digital world of computing, a virtual machine (VM) is an emulation of a particular computer system. Virtual PC machines run on computer architecture and make use of functions from a real or hypothetical computer where their executions may involve specialized hardware, software, or a combination of both. Meaning to say, a virtual machine is a program that acts as a virtual computer whereby it runs on your current operating system ' the host operating system ' and provides virtual hardware to guest operating systems.

A virtual machine is a software computer that, like a physical computer, runs an operating system and applications. The virtual machine is comprised of a set of specification and configuration files and is backed by the physical resources of a host. Every virtual machine has virtual devices that provide the same functionality as physical hardware and have additional benefits in terms of portability, manageability, and security. A virtual machine consists of several types of files that you store on a supported storage device. The key files that make up a virtual machine are the configuration file, virtual disk file, NVRAM setting file, and the log file.

There are different kinds of virtual machines:

System virtual machines -  These VMs also termed full virtualization VMs. These machines provide a substitute for a real machine. They provide the functionality needed to execute entire operating systems.

Process virtual machines - These are designed to execute computer programs in a platform-independent environment.


Some virtual machines, such as QEMU, are designed to also emulate different architectures and allow execution of software applications and operating systems written for another CPU or architecture. Operating-system-level virtualization allows the resources of a computer to be partitioned via the kernel. The terms are not universally interchangeable.

How virtual machines are work?

Virtual machines are built to furnish users with their own virtual hardware, including a virtual CPU, memory, hard drive, network interface, and other devices. The virtual hardware devices provided by the virtual machine are pasted to real functioning hardware on your physical machine. For instance, a virtual computer's virtual hard disk is stored in a file that is found on your hard drive.


Most virtual machines are hosted on, or works inside of, a physical machine. For a virtual machine to work, the hosted physical machine provides software called hypervisor. The hypervisor virtualizes, or emulates, components of the physical machine by dividing a part of CPU, memory, hard disk and network and assign these for the virtual machine. The OS on the virtual machine recognizes these components as the ones to construct computer and thus uses them to run OS and application on the virtual machine.

After installing operating systems into your virtual machines, you can open your virtual computer program and choose which virtual machine you want to boot only when the guest operating system is activated and runs in a window on your host operating system.

Advantages of a virtual machine include:

  • Allows multiple operating system environments on a single physical computer without any intervention.
  • Virtual machines are widely available and are easy to manage and maintain.
  • Offers application provisioning and disaster recovery options.

Disadvantages of virtual machines include:

  • They are not as efficient as a physical computer because the hardware resources are distributed in an indirect way.
  • Multiple VMs running on a single physical machine can deliver unstable performance.
  • A virtual machine can be infected with the weaknesses of the host machine. As an example, process isolation is a feature usually employed by operating systems. However, there are bugs that violate it. A regular computer devoid of virtual machines would then only be affected. But, a computer with a number of virtual machines would then infect each of those “machines” as well.

Applications of Virtual Machines

  • There is an emerging trend among the IT community where users store their desktop applications and operating systems in a separate virtual machine in the server and use their PC as a "thin client" to the server. Each user is isolated from all other users with the help of virtual machine technology, and the maintenance of the applications is shifted from each user's desktop to the datacenter.

  • Virtual machines are like transferrable self-contained packages. It is relatively easy to move a Virtual Machine from one server to another to balance the workload, to migrate to faster hardware, as well as to recover from hardware failure.

  • With Virtual Machines, you can adopt a safe method in running the development version of Windows 10 on your Windows 8 computer. This method allows you to run a trial with Windows 10 without installing an unstable version of Windows on your computer.

  • You can also install different distributions of Linux or other lesser known operating systems in a virtual machine to experiment with them and to understand how they work.

  • Mac and Linux users can also run Windows in a virtual machine to run Windows software on their computers without the compatibility headaches of Wine and Crossover.

  • With virtual machines, it eliminates the need to dedicate a single machine to one application.

  • In a situation where you have an important application that only runs on Windows XP, you can install XP in a virtual machine and run that rather prehistoric application in the virtual machine where compatibility isn't an issue.

  • The best part is that virtual machines allow you to use an application that only works with Windows XP without actually installing Windows XP on your computer which is definitely handy since not many hardware fully support Windows XP.


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