VM

What most cell phone services use for leaving voice messages.

VM stands for "Virtual machine," which is software that emulates a computer system and is run on a separate "host" computer system. Software developers often utilize VMs to test programs in multiple operating system (OS) states on one physical computer.

A VM performs much of the same functionality as a physical machine but instead of running directly on the hardware of the computer, it is controlled by a virtualization application. Some examples of virtualization software include Parallels Desktop and VMware Workstation Pro.

One example of VM usage is a software developer who needs to test out the performance of his application in different versions of Windows. He can install and save various versions of Windows, like XP, 7, 8, and 10 on different VMs and install and run in his application.

Another example is when a Mac user needs to run software that only runs in Windows. She can install the Windows OS in a VM in macOS, then run the Windows-only program in a VM through an application window. And if anything becomes corrupt in the VM, she can easily reset the VM without affecting her computer.