Editing Virtual machine (section)

{{Short description|Software that emulates an entire computer}}
{{Use dmy dates|date=June 2019|cs1-dates=y}}
[[File:Virt-manager_3.2.0_QEMU_KVM_screenshot.png|thumb|upright=1.35|''[[virt-manager]]'' running the [[Haiku (operating system)|Haiku]] operating system in a window]]
{{Program execution}}
In [[computing]], a '''virtual machine''' ('''VM''') is the [[virtualization]] or [[emulator|emulation]] of a [[computer system]].  Virtual machines are based on [[computer architecture]]s and provide the functionality of a physical computer. Their implementations may involve specialized hardware, software, or a combination of the two.
Virtual machines differ and are organized by their function, shown here:

* ''[[System virtual machine]]s'' (also called [[full virtualization]] VMs, or SysVMs,<ref>{{cite thesis |last=Dittamo |first=Cristian |title=On Expressing Different Concurrency Paradigms on Virtual Execution Systems |type=Ph.D. thesis |publisher=University of Pisa |date=2010 |url=https://www.researchgate.net/publication/221028529_On_Expressing_Different_Concurrency_Paradigms_on_Virtual_Execution_Systems |access-date=12 May 2025}}</ref>  provide a substitute for a real machine. They provide the functionality needed to execute entire [[operating system]]s. A [[hypervisor]] uses [[native code|native execution]] to share and manage hardware, allowing for multiple environments that are isolated from one another yet exist on the same physical machine. Modern hypervisors use [[hardware-assisted virtualization]], with virtualization-specific hardware features on the host [[CPU]]s providing assistance to hypervisors.
* ''[[Process virtual machine]]s'' are designed to execute computer programs in a platform-independent environment.

Some virtual machine emulators, such as [[QEMU]] and [[video game console emulator]]s, are designed to also emulate (or "virtually imitate") different system architectures, thus allowing execution of software applications and operating systems written for another CPU or architecture. [[OS-level virtualization]] allows the resources of a computer to be partitioned via the [[Kernel (operating system)|kernel]]. The terms are not universally interchangeable.