Virtualisation is software that creates fake computers inside a real one. Each fake computer (called a virtual machine) runs its own operating system and software independently, as if it were a genuine separate device.
Think of it like running multiple rooms inside a single building. Each room has its own walls, door, and furniture, but they all share the same roof, foundation, and heating system. The physical computer is the building; the virtual machines are the rooms.
Common uses include:
- Running Windows and macOS on the same Mac or PC for work and testing
- Letting server computers host dozens of websites or services without buying dozens of machines
- Protecting your main system: if a virtual machine catches a virus, your real computer stays safe
- Running old software that your current operating system no longer supports
Popular virtualisation tools for home users include VirtualBox (free), Parallels Desktop (Mac), and VMware Fusion. Servers use more powerful versions like Hyper-V and KVM.
The downside: virtual machines are slower than real computers because they share the host's processing power, storage, and memory. You need enough resources to run multiple systems comfortably. When choosing virtualisation software, check your computer's specifications (particularly RAM and CPU cores), compare feature sets, and decide whether you need support for specific operating systems.