What are virtual machines used for?

<ul><li><strong>Software development:</strong> Testing software in multiple environments.</li><li><strong>Cybersecurity: </strong>Running penetration tests or analyzing malware safely.</li><li><strong>Legacy systems:</strong> Running outdated applications on older operating systems.</li><li><strong>Education</strong>: Experimenting with different OS without purchasing additional hardware.</li></ul>

Why is my VM running slowly?

<h3>Several factors can slow down a VM:</h3><ul><li>Insufficient RAM or CPU allocation.</li><li>High disk usage on the host machine.</li><li>Too many VMs are running simultaneously.</li><li>Outdated virtualization software or VM OS.</li></ul><br>

Virtual Machines 101: What They Are and How to Use Them Securely

Written by: Lizzie Danielson

Published: June 17, 2025

Virtual machines (VMs) are a game-changer in today’s landscape. Whether you're a developer, IT specialist, cybersecurity professional, or just a curious tech-gamer enthusiast, understanding virtual machines can open new doors to efficiency, security, and experimentation. But with these benefits come some unique challenges and risks that you need to keep in mind.

This blog will walk you through everything there is to know about virtual machines—from what they are and how to use them, to troubleshooting performance and ensuring security. By the time you’re done, you’ll not only understand VMs but also know how to use them effectively

Key Takeaways

A virtual machine (VM) is a software emulation of a physical computer that runs its own operating system and applications in an isolated environment on shared hardware — multiple VMs can run simultaneously on a single physical server.
VMs run on a hypervisor: Type 1 hypervisors (bare-metal, like VMware ESXi or Microsoft Hyper-V) run directly on server hardware; Type 2 hypervisors (hosted, like VirtualBox or VMware Workstation) run on top of a conventional host OS.
The isolation between a VM and its host system is a security strength — malware inside a VM typically cannot affect the host. VM escape vulnerabilities, where an attacker breaks this boundary, are rare but critical when they occur.
Security teams use VMs extensively for sandboxing suspicious files, running malware analysis in controlled environments, testing patches before production deployment, and isolating legacy systems that can't be updated.
Attackers increasingly target virtualization infrastructure directly — hypervisor vulnerabilities, misconfigured management interfaces, and VM sprawl (unmanaged, forgotten VMs) are common attack paths in enterprise environments.
VM snapshots allow rapid rollback to a clean state after compromise, making VMs valuable for incident response and security testing — but outdated snapshots can also preserve vulnerable configurations if not managed carefully.

What is a virtual machine?

At its core, a virtual machine (VM) is a software-based emulation of a physical computer. It creates a virtual environment that runs its own operating system (OS) and applications independently from your primary hardware (often referred to as the “host” machine).

Think of a VM as a sandbox. It’s self-contained, which means everything is inside it, including the OS, the files, and apps which are separated from the host computer.

How does it differ from a physical machine?

The main difference comes down to tangibility. A physical machine (like your laptop, desktop, or server) is hardware-dependent. A VM, on the other hand, is software-defined and runs on a physical machine but functions as independent hardware.

Here are some key differences to note:

Flexibility: VMs can run multiple operating systems on a single physical machine.
Isolation: They operate in a confined virtual environment, so if configured properly, errors or viruses inside a VM don’t affect the host.
Immobility (Physical Machine): A physical machine can’t be moved or cloned, unlike VMs, which can be replicated and migrated easily.

What are the benefits of using virtual machines?

Virtual machines bring a ton of value to the table, including:

Testing & experimentation: Developers can test new code or software in a safe, isolated environment without risking their primary system.
Cost efficiency: VMs allow multiple “computers” to run on a single physical machine, reducing hardware and maintenance costs.
Disaster recovery: Virtual machines can be backed up and restored easily.
Cross-platform compatibility: You can run Windows on a Mac or Linux on Windows with VMs.

What are the drawbacks of using virtual machines?

Like any tool, VMs aren’t without limitations:

Performance overhead: VMs rely on the host machine’s resources, which can cause slower performance if overutilized.
Complex setup: Setting up VMs can be challenging, especially for beginners unfamiliar with virtualization software or resource allocation.
Security risks: While isolated, poorly configured VMs can still be vulnerable to threats, especially if connected to a network.

Setting up and configuring a virtual machine

Step 1: Choose your virtualization software

To get started with VMs, you'll need virtualization software. Some popular options include:

VMware (for advanced configuration and enterprise-level use)
VirtualBox (free and beginner-friendly)
Microsoft Hyper-V (ideal for Windows users)

Step 2: Create your virtual machine

Install your chosen virtualization software.
Choose the operating system (e.g., Windows, Linux, macOS) you want to run on the VM.
Follow your software's guided setup to configure storage, memory, and CPU.

Step 3: Allocate resources

Allocating resources depends on what you’ll be doing inside the VM. Here’s a general rule of thumb:

RAM: Allocate at least 4GB for standard use, or more for resource-heavy applications.
CPU Cores: Assign at least 2 cores for a smoother experience.
Disk Space: Allocate 20GB or more, depending on your software and files.

Step 4: Running Multiple VMs

Yes, you can run multiple VMs simultaneously, but this is resource-intensive. Ensure your host machine has sufficient CPU and RAM to avoid throttling.

Networking and security for virtual machines

Networking between VMs is generally configured through the virtualization software:

Bridged mode: Connects VMs directly to your network, granting them individual IPs.
NAT mode: Uses the host’s IP address for connections but isolates VMs from external access.

VM vs. Container

	Virtual Machine	Container
Isolation level	Full OS-level isolation — each VM has its own OS kernel	Process-level isolation — all containers share the host OS kernel
Security boundary	Stronger — VM escape requires exploiting the hypervisor	Weaker — shared kernel means a container escape is a smaller attack surface gap
Startup time	Minutes (full OS boot required)	Seconds (no OS boot — just process startup)
Resource usage	Higher — each VM includes a full OS with memory and CPU overhead	Lower — shared kernel with minimal per-container overhead
Portability	Less portable — platform and hardware dependencies	Highly portable via container images (Docker Hub, OCI)
Common examples	VMware ESXi VMs, AWS EC2 instances, Azure Virtual Machines	Docker containers, Kubernetes pods
Best for	Strong isolation requirements, legacy OS support, full OS testing	Microservices, cloud-native applications, CI/CD pipelines, rapid scaling

Can a VM get viruses?

Absolutely. A VM functions like any other computer, so it can be infected with viruses if exposed to malicious files or websites. However, the good news is that virus activity is contained within the VM and doesn’t usually harm the host machine in most cases.

Tips for securing virtual machines

Use snapshots: Take periodic snapshots of your VM so you can revert to a clean state if needed.
Follow basic cyber hygiene: Install antivirus software, enable firewalls, and keep your VM OS updated. If you don’t already have a security hygiene plan in place, we recommend you view this blog here.
Isolate Critical VMs: Avoid networking VMs unnecessarily to reduce exposure to threats.

Safely virtualizing your way forward

Virtual machines are a versatile tool that can benefit individuals and businesses alike. From safer web browsing to scalable enterprise solutions, the use cases for VMs are nearly limitless. But don’t be fooled by their versatility; setting up a VM properly and following best practices for security is essential to making the most of them.

FAQs about virtual machines

A virtual machine (VM) is a software emulation of a physical computer. It runs its own operating system and applications in an isolated environment on shared physical hardware, managed by a hypervisor. Multiple VMs can run simultaneously on a single server, each behaving as an independent computer. VMs enable better hardware utilization, easier workload isolation, and faster disaster recovery through snapshots and replication.

Software development: Testing software in multiple environments.
Cybersecurity: Running penetration tests or analyzing malware safely.
Legacy systems: Running outdated applications on older operating systems.
Education: Experimenting with different OS without purchasing additional hardware.

While both VMs and Docker enable isolation, Docker is better suited for lightweight, containerized applications. However, VMs are ideal when you need a fully functional OS

Yes! Though gaming on a VM comes with limitations (e.g., reduced graphics performance), advancements in GPU passthrough now make it feasible for certain setups.

Absolutely. Many security-conscious users browse the web via a VM to isolate their primary system from potential threats.

Several factors can slow down a VM:

Insufficient RAM or CPU allocation.
High disk usage on the host machine.
Too many VMs are running simultaneously.
Outdated virtualization software or VM OS.

The number of VMs you can run depends entirely on your hardware specifications. For most systems, running 2–3 VMs concurrently is realistic with mid-range specs. Servers will handle significantly more.

Additional Resources

What is a VoIP network and why does it matter in cybersecurity?

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What Is Debug Logging? Benefits & Best Practices

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Learn what debug logging is, how it helps in cybersecurity, and key best practices to reduce risk and boost incident response

Vulnerability Management Lifecycle: Steps and Best Practices

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Learn the steps in vulnerability management, how to assess and prioritize risks, the best tools, and tips for a strong vulnerability management lifecycle.

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Virtual Machines 101: What They Are and How to Use Them Securely

Key Takeaways

What is a virtual machine?

How does it differ from a physical machine?

What are the benefits of using virtual machines?

What are the drawbacks of using virtual machines?