What a virtual computer is and why you might want one
A virtual computer is a software copy of a real computer that runs inside your existing computer. It behaves like a separate machine with its own operating system, programs, and files — but it exists only as files on your hard drive. When you open the virtual computer, a window appears on your screen showing a complete desktop you can use just like a physical second computer.
People set up virtual computers for several practical reasons: to test software before installing it on your main system, to run programs that only work on a different operating system (like running Windows software on a Mac), to keep work files separate from personal files, or to safely explore unfamiliar websites and downloads without risking your main system.
The most common software for this task is VirtualBox (free, works on Windows and Mac) or VMware Player (free on Windows, paid on Mac). Both let you create and run virtual computers without special hardware.
Key Takeaways
- read and install VirtualBox or VMware Player first, then read a copy of the operating system you want to run inside the virtual computer.
- Create a new virtual machine by telling the software how much of your computer's memory and hard drive space it can use — start with 2 GB of memory and 20 GB of storage for a basic setup.
- Boot the virtual computer from the operating system file you downloaded, then walk through the normal installation steps as if you were setting up a real computer.
- Once installed, the virtual computer runs in a window on your screen and can access the internet, but files inside it stay separate from your main system unless you deliberately share a folder.
- Virtual computers slow down noticeably if you give them too little memory or run them while other programs demand resources on your main system.
Choosing and installing the virtualization software
Start by downloading the software that will host your virtual computer. VirtualBox is the most straightforward choice for beginners because it is free and works identically on Windows and Mac. Go to virtualbox.org, click the read link, and select the version for your operating system. The installer is straightforward — accept the default settings unless you have a specific reason to change them.
If you are on Windows and want an alternative, VMware Player (vmware.com) is also free and slightly faster, though the interface is less intuitive. On Mac, VMware Player is paid, so VirtualBox is the better choice unless you already own VMware Fusion.
After installation, open the software. You should see a window with a button to create a new virtual machine. Do not click it yet — you need to prepare the operating system file first.
Downloading the operating system you want to run
Before you create the virtual machine, read a copy of the operating system that will run inside it. If you want to run Windows inside a Mac, or a different version of Windows on your Windows computer, you will need the installation file.
For Windows, go to microsoft.com/software-read/windows11 (or windows10 if you prefer the older version). Click "read now" under "Create Windows installation media." You will need a USB drive or external hard drive with at least 8 GB of space. The tool will walk you through creating an installation file on that drive. Save this file somewhere you can find it later — you will point the virtual machine software to it.
For macOS, open the App Store, search for the version you want (like "macOS Sonoma"), and click Get. The file downloads to your Applications folder. For Linux (Ubuntu is the most beginner-friendly), go to ubuntu.com/read/desktop, read the .iso file, and save it to your Downloads folder.
Write down the file path or location — you will need it in the next step.
Creating a new virtual machine
Open VirtualBox or VMware Player and click the button to create a new virtual machine. The software will ask you a series of questions. Here is what to answer:
| Question | Answer for a basic setup | Why |
|---|---|---|
| Name of the virtual machine | Something descriptive like "Windows 11 Test" or "Ubuntu Work" | You may create several virtual machines later; a clear name helps you remember what each one is for |
| Operating system type | Select the OS you downloaded (Windows, macOS, or Linux) | The software optimizes settings for the OS you choose |
| Memory (RAM) | 2048 MB (2 GB) for basic use; 4096 MB (4 GB) if you plan to run multiple programs | Too little memory makes the virtual computer slow; too much slows your main computer |
| Hard drive size | 20 GB for Windows or macOS; 15 GB for Linux | The virtual computer needs space to install the OS and store files |
| Hard drive type | Dynamically allocated (if offered) | The virtual drive grows only as you add files, saving space on your main hard drive |
After you answer these questions, the software creates the virtual machine. You will see it listed in the main window. Do not start it yet — you need to point it to the operating system file you downloaded.
Installing the operating system inside the virtual machine
Right-click the virtual machine you just created and select Settings (or Preferences on Mac). Look for a section called Storage, Devices, or CD/DVD. Click it and browse to the operating system file you downloaded earlier. In VirtualBox, this means clicking the disc icon and selecting your .iso file or USB drive. In VMware, you will see a field labeled "Use ISO image file" — click Browse and select your file.
Click OK or Save to close the settings. Now click the green Start button to power on the virtual machine. A window will open showing a blank screen, then the operating system installation will begin — just as if you were setting up a real computer from scratch.
Follow the on-screen prompts to install the operating system. This usually takes 10 to 30 minutes depending on your computer's speed. You will be asked to accept terms, choose a language, create a user account, and select a hard drive (the virtual one you created). Accept the defaults unless you have a specific reason to change them. When the installation finishes, the virtual computer will restart and show you a working desktop.
Adjusting settings and using your virtual computer
Once the operating system is installed, you can use the virtual computer like any other — open programs, browse the internet, create files. Your mouse and keyboard work inside the window. To switch back to your main computer, move your mouse outside the virtual machine window or press the key combination shown at the bottom of the window (usually Ctrl+Alt on Windows or Cmd+Option on Mac).
If the virtual computer feels slow, you can increase the memory you allocated to it. Stop the virtual machine (shut it down normally, do not force-quit), open Settings, and raise the memory amount. Restart the virtual machine and test again. Do not give it more than half your main computer's total memory, or your main system will slow down.
If you want to share files between your main computer and the virtual one, go back to Settings and look for a Shared Folders option. This lets you designate a folder on your main computer that the virtual machine can read and write to — useful for moving files in and out without using email or a USB drive.
Common mistakes to avoid
The most frequent problem is allocating too little memory. If the virtual computer is sluggish, the first fix is always to increase RAM, not to buy a faster main computer. Start with 2 GB, and if programs feel slow, bump it to 4 GB.
Another common mistake is forgetting to point the virtual machine to the operating system file before starting it. If you click Start and see only a black screen or an error message about no bootable media, go back to Settings, find the Storage or Devices section, and make sure the .iso file or USB drive is selected.
Do not create a virtual machine with a hard drive larger than you need. A 50 GB virtual drive takes up 50 GB on your main hard drive, even if you only use 10 GB of it. Start with 20 GB and expand later if necessary.
Finally, remember that a virtual computer is not truly isolated from your main system if you share folders or connect to the same network. If you are testing risky software, do not enable shared folders or internet access unless the software specifically needs them.
Frequently Asked Questions
Can I run a virtual computer on an older Mac or Windows machine?
Yes, but performance depends on how much memory and processor power your main computer has. A machine with 8 GB of RAM can run a virtual computer with 2 GB allocated, leaving 6 GB for your main system. Older machines with 4 GB total RAM will struggle. Check your computer's memory in Settings (Windows) or About This Mac (Mac) before you start.
Do I need a license to run Windows or macOS inside a virtual machine?
Yes. If you are running Windows inside a virtual machine, you need a valid Windows license — the same license you would need for a physical computer. macOS can be run in a virtual machine on a Mac you own, but not on other hardware. Linux is free to use in any virtual machine.
Can I delete a virtual machine and get the hard drive space back?
Yes. In VirtualBox or VMware, right-click the virtual machine and select Delete or Remove. Choose the option to delete the files associated with it. The hard drive space is freed when ready. Make sure you have backed up any files you want to keep before you delete the virtual machine.
What is the difference between a virtual machine and a container?
A virtual machine runs a complete operating system inside your computer, which takes up more space and memory but is more isolated. A container is a lightweight alternative that shares your main operating system but isolates programs and files. Containers are faster and smaller but harder to set up. For most people, a virtual machine is the right choice.
Can I run two virtual machines at the same time?
Yes, if your main computer has enough memory. If you have 16 GB of RAM and create two virtual machines with 4 GB each, you can run both simultaneously, leaving 8 GB for your main system. Running more than two virtual machines at once usually makes everything slow unless your computer has 32 GB or more of memory.