2. Operating systems on a virtual machine

Just like regular computers, you can install an operating system on a virtual machine. This will let you install and run software which needs to use that operating system.

The screenshot below shows a Windows XP virtual machine running on a Windows 10 computer. The virtual machine contains the XP operating system and XP applications will run exactly as if they were on a real, hardware-based computer.

You can use virtual machines to run many other types of operating systems, such as Linux. You can even use them to run operating systems that were never intended to be installed on a personal computer, like mobile phone or gaming console operating systems.

The only limitation is that you cannot create a virtual machine that requires more hardware resources than your real computer actually has. You could not, for example, use virtual machines to run desktop computer programs on the tiny processor of a handheld calculator.

Benefits and uses

• You can run older applications that are not compatible with newer operating systems.
• You can run multiple operating systems on the same computer.
• Virtual machines are very easy to copy and back up once they're installed. Reverting to backups of virtual machines is simple.
• Shielding malware. If you run a business, you could use virtual machines to open files you think might contain malware but nevertheless need to make sure that it is not a legimitate order. For example, a suspect pdf sales order received by email. You set up the VM to be entirely independent of the host, so even if the virtual machine is infected, your real computer will be unaffected. Once the order is viewed (legitimate or not), the VM 'instance' is deleted as a matter of routine and a fresh version is used next time.
• Web hosting companies can create and sell many 'virtual servers' within a single physical server

Disadvantages

• Programs will run less efficiently (ie more slowly) on a virtual machine than they would on the original hardware.
• You still need proper licences to run the operating system and applications within a VM - they are as applicable to copyright law as any other, so they cannot just be copied willy-nilly.