What is a hypervisor?
A hypervisor is the software layer that creates and runs virtual machines and shares the real hardware between them.
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A hypervisor is the program that carves one physical computer into several virtual machines and keeps them apart. It is the landlord of the building: it decides how much memory and how many CPU cores each tenant gets and makes sure nobody wanders into a neighbour’s flat. Type 1 hypervisors run directly on the hardware; type 2 hypervisors run as an app on top of a normal operating system.
KVM (built into Linux), VMware ESXi, Microsoft Hyper-V and Xen are type 1. VirtualBox and VMware Workstation are type 2 and are what most people use on a laptop. Proxmox VE and Oracle PCA are management layers around KVM. If a VM feels slow, check whether hardware virtualisation is switched on in the BIOS.
egrep -c '(vmx|svm)' /proc/cpuinfoSee also: What is a virtual machine? and What is a cluster?
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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
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