Virtualization - Definition & Overview

What is Virtualization?

Virtualization is a technology that allows a single physical computer to act like multiple independent computers. It works by using a software layer to "hide" the physical hardware from the operating systems. Instead of an application running directly on the physical chips and wires, it runs inside a digital environment that mimics that hardware.

Virtualization is the foundation of several modern IT models, including:

• Infrastructure as a Service (IaaS)

• Platform as a Service (PaaS)

• Software as a Service (SaaS)

• Virtual Desktop Infrastructure (VDI)

• Edge computing

How Virtualization Works

The key to this process is a piece of software called a hypervisor. The hypervisor sits on top of the physical hardware and acts as a resource manager. It takes the total amount of processing power, memory, and storage available and carves it into smaller, isolated sections called Virtual Machines (VMs).

Even though several VMs might be sharing the same physical server, they are completely isolated from one another. This means you can run different operating systems like Windows and Linux side-by-side on the same machine without them interfering with each other.

By using virtualization, organizations can make much better use of their hardware. Rather than buying ten separate servers that each only do one small job, they can buy one powerful server and virtualize it to do all ten jobs at once. This reduces costs, saves physical space, and makes it much easier to back up or move data.

Components of Virtualization

Different layers work together to abstract hardware, allocate resources, and ensure each virtual machine runs independently on shared physical infrastructure.

Hypervisors and Virtual Machines (VMs)

A hypervisor is a special program that creates and runs virtual machines (VMs).

There are two types:

• Type 1 (Bare-metal): Installed directly on physical hardware (e.g., VMware ESXi, Microsoft Hyper-V).

• Type 2 (Hosted): Runs on top of a host operating system (e.g., VirtualBox, VMware Workstation).

Each virtual machine acts like a real computer. It has its own operating system, a virtual CPU, virtual RAM, virtual storage. Multiple VMs can run on the same hardware without ever interfering with one another.

Hardware Abstraction Layer

The hypervisor also works as a Hardware Abstraction Layer (HAL).

This simply means it hides the messy details of real hardware and gives each VM clean, simple virtual hardware to use.

With technologies like Intel VT‑x, AMD‑V, and IOMMU, VMs can access hardware more efficiently and securely.

Virtual CPU, Memory, and Storage

Each VM gets virtual versions of the main computer parts:

• vCPU: A slice of the physical CPU
• vMemory: A portion of the host machine’s RAM
• vStorage: A file that behaves like a hard disk (e.g., VMDK or VHD)

More advanced setups include features like:

• NUMA‑awareness (better performance on multi‑CPU systems)
• Thin provisioning (saves storage by giving each VM only what it needs)
• Deduplication (removes duplicate data to save space)

Types of Virtualization

Depending on what resource is being abstracted, virtualization generally falls into these five main categories.

Server Virtualization

This involves masking server resources including the number and identity of individual physical servers, processors, and operating systems from server users. A hypervisor divides a single physical server into multiple small, isolated virtual servers.

Desktop Virtualization

Also known as Virtual Desktop Infrastructure (VDI), this technology delivers desktop environments remotely from centralized servers. It supports secure remote work and centralized patching for industries with strict compliance requirements.

Storage Virtualization

Combines physical storage from multiple devices into a single logical pool, increasing redundancy and performance. Implemented via SANs (Storage Area Networks), NAS systems, and hyperconverged infrastructure (HCI). Techniques like thin provisioning, deduplication, and RAID are used to optimize storage performance and availability.

Network Virtualization

Virtualizes networking functions like switching, routing, and firewalling. Enables Software-Defined Networking (SDN) and Network Functions Virtualization (NFV), critical for cloud-native architectures and 5G infrastructure.

Application Virtualization

Allows applications to run independently from the underlying OS, reducing conflicts and easing deployment. Technologies like Citrix Virtual Apps and Microsoft App-V provide sandboxing and centralized management.

Virtualization vs. Containerization

While both virtualization and containerization are used to isolate workloads and optimize resources, they differ significantly in structure and use case. Virtualization emulates entire hardware stacks, allowing multiple operating systems to run on the same physical server. This strong isolation is best for legacy systems, monolithic apps, and environments needing full OS-level control.

Containerization, by contrast, isolates applications at the process level while sharing the host operating system kernel. Containers are lightweight, fast to deploy, and ideal for microservices, DevOps pipelines, and cloud-native apps. While containers are more efficient, they offer less isolation compared to VMs.

Need expert help modernizing your infrastructure? Talk to our virtualization consultants today.