What Is a Virtual Machine?

Did you know you can create a fully functional computer inside of your existing computer? This technology exists everywhere: on your home computer, on commercial servers, and beyond. This technology, known as a virtual machine, uses software to function fully in computing environments. In this article, learn what a virtual machine is, what it's used for, how it works, and why you may or may not want to use one.

What is a virtual machine?

A virtual machine (VM) is a computing resource that relies on software rather than physical resources or hardware to run programs, apps, and processes. On your device, you have two main components: hardware and software.

Hardware is the physical stuff: motherboard, CPU, memory, etc. Hardware decides your system resources, i.e. computing power and data storage amount.

Software is digital. This is the firmware, operating system, and programs that run on physical hardware in binary. To have software, you need hardware to install it on.

A virtual machine uses hardware-based virtualization software. This application mimics computer hardware. In essence, it's computer software pretending to be hardware. So, rather than buying a new device, you can create it on top of your existing operating system (OS).

So when you install a virtual machine, you're installing an operating system onto a software application that the VM OS thinks is hardware. It's essentially a computer within a computer.

In theory, you can create as many virtual machine operating systems as you like, provided you have the system resources. A single server could, for example, run multiple operating systems on computers at once. Unlike physical servers, they can also run different operating systems and versions, such as Windows, Mac, or Linux. Virtual machines allow you to expand your computing capabilities, even to advanced technologies such as quantum computing with the right software.

How do virtual machines work?

A VM is a layer over your existing software. This layer is known as a "hypervisor," which is why professionals often call VMs hypervisor software. Think of the hypervisor as a manager for creating, handling, and controlling virtual machines.

A hypervisor creates an isolated environment for the VM from the physical host machine around it. Thus, a VM does not rely on your host computer for anything other than the hardware and power needed to run it. Everything happening on the virtual machines does not affect the host system on which it sits - or other virtual machines.

VMs allocate resources as needed. A VM can have a set amount of resources, or resources that change dynamically according to its current workload.

How do you use a virtual machine?

When using a virtual machine, it functions as you would expect the operating system in question to work. It gets a portion of your hardware processing power, memory, and storage from the host computer so it has its "own" resources.

It has its own MAC address, IP address, and hardware ID numbers, too. You can also use the same peripherals like your screen, keyboard, and mouse. It is, for its users and the devices that it interacts with, an independent device.

You can do almost anything on a VM that you could do on your real, physical computer. However, you need to be running the VM software for it to work. If you shut down the virtual machine client, or your physical computer is off, the VM is off, too.

A VM exists as data on your computer, same as a software application. You can delete it at any time, at which point it would cease to exist. You can also transfer a virtual machine to another device without much issue.

Types of virtual machines

Two main types of virtual machines exist: Type 1 VMs and Type 2 VMs.

Type 1 hypervisors run on a host machine with direct hardware access. They perform better and are more efficient than type two hypervisors since they minimize overhead. You will mostly see these in server applications.

Type 2 hypervisors run off your host system's operating machine. These are the most common end-user VMs, and work better for specific use cases. Aside from personal use, you might see a developer using this to build or test apps.

There are also process VMs and system VMs. Process virtual machines execute a single process rather than run an entire system to do it. It exists only long enough to execute the process. They're great for temporary tasks that need to be platform-independent.

System virtual machines are a full environment and operating system, ideal for longer-term needs. If you use a virtual machine for personal use, it's probably a type 2 system VM.

What is a virtual machine used for?

Many people use VMs for personal use, but the vast majority of the usage is for commercial IT infrastructure. Large and small companies use virtual machine technology for a wide variety of purposes. Let's look at a few common reasons to use them.

Partitioning resources

The primary use for a VM is to divide up a host device into multiple parts. You may have a server with plenty of resources to spare. Instead of buying a new server to handle an additional task, you spin up a VM.

This allows one server to fulfill many roles. One of its virtual machines could handle Structured Query Language (SQL) requests, while another could focus on machine learning (ML) services. Each machine is secure and separate from the others, avoiding compatibility errors and security risks.

Testing software or operating systems

It would be costly and wasteful to purchase or build a new server just to try out new software or operating systems. Instead, IT professionals can install it on a VM.

Developers can create a realistic testing environment or multiple testing environments. Each has different operating systems, configurations, user agents, and so on. Bug testing for customer software works great in a VM.

This allows them to get a practical idea of how the software or operating system would work in real-life scenarios, without building a separate machine. Plus, any bugs or security threats would remain inside the virtual machine without affecting surrounding bare-metal systems.

Quarantining infected software

Malicious software can spread to an entire system when opened or diagnosed. Instead of contaminating the host system, the virtual machine can quarantine it for analysis.

Benefits of virtual machines

Why bother using VMs over physical machines? VMs are a mainstay in the IT industry - and for personal use - due to the following reasons.

• Efficiency and cost savings. Many servers have plenty of resources that never see any use. Virtualization makes sure they don't go to waste. It saves money since there's no need to buy additional machines, provided there are enough resources.
• Streamlining workflow. Virtual machines make it very, very easy to deploy applications and operating systems in all sorts of environments and conditions with ease. For IT managers and developers, there's no easier way to do this.
• Scalability and flexibility. VMs make it easy to scale up and down to accommodate workloads in flux. Plus, they don't need specific hardware specifications since a hypervisor can, in most cases, fabricate to taste on the fly.
• Better security. Due to their inherent isolation, VMs keep systems secure. They prevent malware from spreading from one system to another.

Virtual machines work like physical machines when it comes to backup, too. It's easy to roll back a compromised or broken virtual machine without losing it.

Drawbacks of virtual machines

Virtual machine software has many benefits, but it isn't perfect. First, they have limited resources. A VM uses the resources of the host system. In order to continue running, the host computer cannot give all of its resources; it can only provide a portion of them.

Obviously, you can't give a VM more resources than you have. You also cannot create resources that don't exist. If you need to emulate a graphics card, you would need a graphics card with enough resources to mimic it. Having no GPU (or an underpowered GPU) would prevent you from doing this.

Virtual machines also have performance issues. Since the host computer is giving up part of its resources, this limits the resources for everyone. If the VM and/or the host system are under a heavy load, the performance of both may suffer. Internet speed partitioned among multiple systems would, for example, get slower if all systems are experiencing heavy throughput.

Hypervisors intelligently reallocate resources to prevent this. If there's no other hardware or system to handle a heavy task load, though, you are out of options. Further, having too many VMs running at the same time will degrade performance if there are not enough resources.

Furthermore, Type 2 System virtual machines (those running on the OS) have overhead, which are the extra demands of running a VM unrelated to VM or a host operating system's normal necessary processes. Most of the time this overhead is negligible. It's only under heavy load that the overhead could take a toll performance-wise.

Finally, virtual machines have limited independence. Since a VM runs on an existing computer, it does not exist without it. If the host system isn't running, or experiences issues, this will stop or limit the machine.

Frequently asked questions

What is the Java virtual machine launcher error?

The Java virtual machine launcher error is an error that occurs with the Java virtual machine launcher, often for Minecraft users. It indicates that your computer can't read the code you're trying to execute. If you experience the issue, make sure that you have Java installed correctly and try running the program as an administrator instead.

What is an example of a virtual machine?

An example of a virtual machine is VMWare Workstation or VirtualBox.

Is it legal to use a virtual machine?

Yes, it's perfectly legal to use a virtual machine, virtual servers, or virtual computers. Working in a virtual environment is not a crime as long as you don't commit explicitly criminal acts using those tools.