What Is Virtualization? Definition, How It Works, and Types

Virtualization is the process of creating virtual computers that share the computational power and hardware resources of a single physical machine. A software layer called a hypervisor sits between the hardware and the user, dividing physical resources into isolated virtual environments. Each environment behaves like an independent computer with its own operating system, applications, and files.

How Virtualization Works

Think of the virtualization layer as a middle manager. It oversees the physical computer’s resources and distributes them to each virtual environment while keeping every environment separate, secure, and performing as expected.

The proper name for this layer is a hypervisor. It takes physical hardware components, such as processors, Random-Access Memory (RAM), storage drives, graphics cards, and network interface cards, and configures them into virtual resources that it assigns to each virtual machine.

Because the hypervisor handles this allocation, multiple virtual machines can run on a single physical computer at the same time. Each one can host a different operating system. A single server might run a Windows Server^® VM, two Linux VMs, and a test environment side by side, all drawing from the same set of hardware.

Every virtual machine needs the same kinds of resources a regular computer does: CPU cycles, memory, storage, and network access. The difference is where those resources come from. Instead of dedicated physical components, the hypervisor carves them out of a shared pool.

What Is Computer Virtualization?

Computer virtualization is the practice of running one or more complete virtual computers on a single physical machine. Each virtual computer, usually called a virtual machine (VM), includes its own virtual CPU, memory, storage, and operating system, yet exists entirely as software.

The term covers the broad concept. In practice, virtualization splits into more specific categories depending on what gets virtualized:

• Desktop virtualization delivers full desktop environments to users from centralized infrastructure rather than local machines.
• Server virtualization divides one physical server into several independent virtual servers.
• Application virtualization runs individual applications in isolated containers without installing them on the local device.

A useful way to keep the distinction straight: computer virtualization describes the technology itself, while the categories above describe what you apply it to. When someone virtualizes a server, a desktop, or an application, they are performing computer virtualization at a different layer of the stack.

Here is how a virtual machine compares to the physical computer it runs on:

A virtual machine delivers the function of a physical computer without the physical constraints.

Types of Virtualization

Virtualization applies at several layers of an IT environment, and most organizations use more than one type at once.

Desktop virtualization moves the entire user desktop into a data center or the cloud. Users connect from any device and see the same environment every time. This is the model behind desktop virtualization services and Desktop as a Service (DaaS).

Server virtualization is the most established type. It lets one physical server do the work of several, which is why data centers adopted server virtualization long before virtual desktops became common.

Application virtualization isolates a single program instead of a whole desktop. The application runs on central infrastructure and streams to the user’s screen, so nothing gets installed locally. Read more about how application virtualization works.

Storage virtualization pools capacity from multiple physical drives into a single virtual storage resource. To users, it looks like an ordinary drive, so saving files, backups, and recovery all work the way they expect.

Network virtualization combines physical network equipment, such as routers and switches, into a software-defined network that can be split into independent virtual networks. Each virtual network handles its own functions without dedicated hardware, which cuts down the physical components an organization has to buy and maintain.

Why Use Virtualization?

The main reason is resource sharing. One set of physical hardware serves multiple virtual machines, which reduces the time, cost, and energy spent buying and maintaining separate physical computers for every workload.

Two other benefits follow from how the hypervisor manages each environment:

• Efficiency increases because teams can run multiple virtual machines in parallel on the same hardware. A developer can test software across three operating systems without owning three computers.
• Security issues stay contained because each virtual machine is isolated from the others. If malware infects one VM, the hypervisor prevents it from spreading to its neighbors, and administrators can shut down, snapshot, or rebuild the affected environment without touching anything else.

Virtualization also makes environments portable. A virtual machine is ultimately a set of files, so it can be copied, moved between physical hosts, or restored from a backup far faster than any physical computer could be rebuilt.

Cloud hosting is built on this foundation. Providers use virtualization to divide large pools of data center hardware into virtual resources, then deliver storage and computing power to many customers over the Internet. Every cloud desktop, cloud server, and cloud application traces back to a hypervisor allocating shared hardware.

Virtualization Frequently Asked Questions

How does virtualization reduce costs?

Virtualization lets multiple virtual machines share one set of physical hardware, so organizations buy and maintain fewer physical computers. Provisioning a new virtual machine takes minutes instead of the days required to purchase and set up physical equipment, which also cuts labor costs.

Is cloud hosting the same as virtualization?

Not exactly. Virtualization is the underlying technology, and cloud hosting is a service built on top of it. Cloud providers use virtualization to divide data center hardware into virtual resources, which customers then access over the Internet as storage, computing power, or full desktops.

What is network virtualization?

Network virtualization combines physical network equipment, such as routers and switches, into a single software-defined network that can be divided into independent virtual networks.

Each virtual network runs its own functions, like file sharing and IP configuration, without depending on dedicated hardware. This reduces the number of physical components an organization needs to buy and maintain.