What is a virtual machine?
A virtual machine is a complete computer made of software, running inside another computer with its own operating system.
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A virtual machine (VM) is a software copy of a whole computer: it has virtual disks, virtual memory and virtual network cards, and it runs a full operating system. Think of a house with several self-contained flats; each tenant has their own kitchen and locks, yet they all share one building. The building is the physical server, the flats are the VMs.
VMs power most of the cloud and most company data centres. You meet them when you rent a server from a cloud provider, run Windows inside macOS, or build a home lab on Proxmox. They isolate workloads strongly, can be paused, cloned and moved between hosts, but each one carries a full operating system, so they are heavier than containers.
virsh list --all
qm listSee also: What is a hypervisor? and What is a container?
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See also
- 0098 What Proxmox VE is: KVM virtual machines, LXC containers and a web UI Proxmox VE is an open source virtualization platform based on Debian. It runs KVM virtual machines and LXC containers and is managed… Beginner · Explains an idea · Linux Article Basics · Installation & first steps 15 Oct 2026
- 0100 Create a VM and a cloud-init template with qm Create KVM virtual machines from the command line with qm, then build a reusable cloud-init template from a cloud image and clone… Intermediate · Step by step · Linux Article Basics · VMs & containers 15 Oct 2026
- 0123 KVM vs QEMU vs libvirt: how Linux virtualization fits together KVM is the Linux kernel part that uses CPU virtualization extensions, QEMU is the program that emulates a full machine around it,… Beginner · Explains an idea · Linux Article Basics 15 Oct 2026
- 0124 virsh cheat sheet: everyday libvirt commands A quick reference for virsh: list, start, stop and inspect VMs, change CPUs and memory, manage networks, storage pools and snapshots, with… Intermediate · Cheat sheet · Linux Article Basics 15 Oct 2026
- 0125 Create a KVM virtual machine with virt-install Use virt-install to create libvirt/KVM guests: install from an ISO, run a text-only install over the serial console, or import a cloud… Intermediate · Step by step · Linux Article Basics 15 Oct 2026
- 0126 KVM snapshots and cloning with virsh and virt-clone Take, list, revert and delete libvirt snapshots with virsh, understand internal vs external and disk-only snapshots, and clone a stopped VM with… Advanced · Step by step · Linux Article Basics 15 Oct 2026
Repos in the wild
- proxmox/qemu-server: the Proxmox VE virtual machine manager proxmox/qemu-server Read-only GitHub mirror of qemu-server, the Proxmox VE package that manages QEMU/KVM virtual machines and provides the qm and qmrestore commands. GitHub
- libvirt: virtualization API and daemon (GitHub mirror) libvirt/libvirt libvirt is the toolkit that manages KVM/QEMU and other hypervisors through one API, plus the virsh client. The GitHub repository is a read-only mirror; development happens on GitLab. GitHub
History
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