What is a hypervisor? It is software that lets one physical computer run several virtual machines (VMs) at the same time. It splits the real CPU, memory, disk and network between the VMs and keeps each one isolated from the others. A type 1 hypervisor runs directly on the hardware, while a type 2 hypervisor runs as an app on a normal operating system.
Updated October 2026. This guide replaces the 2009 version with current tools and a home lab focus.
Who this is for: you want to run virtual machines at home or for a small team, and you want to know what the hypervisor does before you pick one.
What is a hypervisor, in plain terms?
Think of the hypervisor as a landlord for one building. The building is your physical server. Each tenant is a virtual machine. The landlord gives each tenant a fixed set of rooms, keeps the doors locked between them, and controls the shared water and power.
Each VM believes it has its own computer. It sees a CPU, some memory, a disk and a network card. In reality, those are slices of the real hardware, or emulated devices that the hypervisor presents. The guest operating system inside the VM does not need to know the difference.
Another name for a hypervisor is a virtual machine monitor (VMM). You will see both terms in documentation. They mean the same job.
The hypervisor is the core of server virtualization. Without it, one server runs one operating system. With it, one server can run a firewall, a file server, a media server and a test box side by side.
Type 1 vs type 2 hypervisor
The split between type 1 and type 2 is about where the hypervisor sits.
Type 1: bare metal
A type 1 hypervisor installs directly on the physical machine. There is no general-purpose desktop operating system underneath it. It boots first and controls the hardware itself. You manage it from a web interface or from another computer on the network.
Examples include Proxmox VE (which uses KVM), VMware ESXi, Microsoft Hyper-V, and Xen-based platforms such as XCP-ng. Servers in data centers almost always run a type 1 hypervisor.
Type 2: hosted
A type 2 hypervisor is an application. You install it on Windows, macOS or Linux, the same way you install a browser. The host operating system controls the hardware. The hypervisor asks the host for resources.
Examples include Oracle VirtualBox, VMware Workstation and VMware Fusion, and Parallels Desktop. These tools suit a laptop or desktop where you also do your normal work.
Side-by-side comparison
| Point | Type 1 (bare metal) | Type 2 (hosted) |
|---|---|---|
| Where it runs | Directly on the hardware | On top of Windows, macOS or Linux |
| Examples | Proxmox VE, VMware ESXi, Hyper-V, XCP-ng | VirtualBox, VMware Workstation, VMware Fusion, Parallels |
| Overhead | Lower, no full desktop OS in the way | Higher, the host OS uses resources too |
| Management | Web UI or remote tools | Desktop app window |
| Runs 24/7 | Yes, designed for it | Only while the host OS runs; usually tied to a desktop session |
| Best for | Home servers, always-on services, small teams | Testing, learning, one-off VMs on your laptop |
| Setup effort | Needs a spare machine you can wipe | Install an app, done |
Where the line blurs
The two labels are a teaching tool, not a strict law. Two common cases cause confusion.
KVM. KVM is a module inside the Linux kernel. Linux itself becomes the hypervisor. Some people call this type 2 because a full OS is present. Most people call it type 1 because the kernel talks directly to the hardware. Proxmox VE is built on KVM, and it behaves like a type 1 hypervisor in practice.
Hyper-V. When you turn on Hyper-V in Windows, the hypervisor loads first, under Windows. Your Windows desktop then runs as a privileged partition on top of it. So Hyper-V is type 1, even though you enable it from a Windows settings screen.
What is Hyper-V?
Hyper-V is Microsoft's hypervisor. It ships with Windows Server. Hyper-V ships with Windows Pro, Enterprise and Education as of October 2026. Check the Microsoft docs, as this can change. Many people search for it because it is already on their PC.
On a Windows desktop, Hyper-V is a quick way to run a Linux VM without a third-party tool. Features such as WSL 2 and Windows Sandbox also use the same virtualization layer. For setup steps and requirements, see the Microsoft Hyper-V documentation.
One side effect: when Hyper-V is active, other desktop hypervisors must share the hardware with it. Recent versions of VirtualBox and VMware Workstation can run alongside Hyper-V, but performance and features can differ. Check each vendor's notes.
How a VM gets CPU, memory, disk and network
The hypervisor has four main jobs. Each one maps to a resource the guest needs.
CPU
You give each VM a number of virtual CPUs (vCPUs). The hypervisor schedules those vCPUs onto real CPU cores, much like an operating system schedules programs. If you give out more vCPUs than you have cores, the VMs take turns. That is normal and often fine, because most VMs sit idle most of the time.
Memory
Each VM gets a block of RAM. The hypervisor maps guest memory addresses to real memory addresses. Some hypervisors can reclaim unused memory from idle guests (ballooning) or merge identical memory pages between VMs. RAM is usually the first limit you hit in a home lab, so plan it first.
Disk
A VM disk is usually a file or a block volume on the host's storage. The guest sees it as a normal hard drive. Formats differ by platform: QCOW2 and raw on KVM, VMDK on VMware, VHDX on Hyper-V, VDI on VirtualBox. Because the disk is a file or volume, you can snapshot it, copy it and back it up.
Network
The hypervisor creates virtual network cards and virtual switches (on Linux, often called bridges). A VM can join your home network as if it were a separate machine. It can also sit on a private internal network that only other VMs can reach. VLANs and firewall rules work here too.
What hardware virtualization (VT-x and AMD-V) does
Early hypervisors used software techniques (binary translation, paravirtualization). That worked, but it was slow. Modern CPUs include features that make virtualization fast and safe.
- Intel VT-x and AMD-V. These let the CPU run guest code directly, with a special mode for the hypervisor. Without them, most modern hypervisors will not run at all, or will run very slowly.
- Second-level address translation. Intel calls it EPT. AMD calls it RVI or NPT. It lets the CPU handle guest memory mapping in hardware, which cuts overhead.
- IOMMU (Intel VT-d, AMD-Vi). This lets you pass a real device, such as a GPU or a disk controller, straight into one VM. Home labs use it for media transcoding and for storage VMs.
Almost every desktop and server CPU from the last decade supports VT-x or AMD-V. The catch is that the feature is often turned off in the BIOS or UEFI by default. If your hypervisor reports that virtualization is not available, check the firmware settings first.
On Linux you can check support with one command. A result above zero means the CPU flag is present:
grep -E -c '(vmx|svm)' /proc/cpuinfoWhich hypervisor type should you use?
Pick based on what the machine does all day.
- You only have your laptop. Use a type 2 hypervisor such as VirtualBox or VMware Workstation. Read the VirtualBox manual to get started. You can learn a lot without spare hardware.
- You have a spare PC or mini PC. Install a type 1 hypervisor. Proxmox VE is the common home lab choice because it is open source and runs both VMs and containers. See what Proxmox VE is and why home labs run it.
- You are on Windows and want one Linux VM. Hyper-V may already be on your machine. Try it before you install anything else.
- You run a small business server. Use a type 1 hypervisor with backups and a support plan you understand. Compare options in Proxmox vs VMware in 2026.
You can also do both. Many people learn on a type 2 hypervisor, then move to a type 1 box once they want services that stay on all the time.
Hypervisors vs containers
A hypervisor virtualizes hardware, so each VM runs its own full kernel. A container shares the host's kernel and only isolates processes and files. Containers start faster and use less memory. VMs give stronger isolation and can run a different operating system, such as Windows on a Linux host.
You do not have to choose one forever. Proxmox runs both KVM virtual machines and LXC containers on the same host. Read containers vs virtual machines for when each one wins. For the wider picture, see the types of virtualization guide.
Common mistakes
- Virtualization is off in the firmware. Turn on VT-x or AMD-V (sometimes called SVM) before you install.
- Giving every VM all the cores. Start small, for example two vCPUs, and add more only if the guest needs them.
- Running out of RAM. Add up the memory for every VM, plus room for the host. Leave headroom.
- Installing a type 1 hypervisor on your only PC. It wipes the disk. Use spare hardware, or start with a type 2 tool.
- Treating snapshots as backups. A snapshot lives on the same disk as the VM. If the disk dies, both are gone. Back up to a separate device.
FAQ
What is a hypervisor in simple terms?
It is software that lets one computer act like many. It divides the real hardware into virtual machines and keeps them apart. Each VM runs its own operating system as if it had its own computer.
What is the difference between a type 1 and type 2 hypervisor?
A type 1 hypervisor runs directly on the hardware, with no desktop OS underneath. A type 2 hypervisor runs as an app inside Windows, macOS or Linux. Type 1 suits always-on servers. Type 2 suits testing on a laptop.
Is Hyper-V a type 1 or type 2 hypervisor?
Hyper-V is type 1. When you enable it, the hypervisor loads below Windows, and Windows runs in a privileged partition. It feels like an app because you turn it on from Windows settings.
Is Proxmox a hypervisor?
Yes. Proxmox VE is a complete virtualization platform built on Debian Linux. It uses KVM for virtual machines and LXC for containers, with a web interface to manage both. It acts as a type 1 hypervisor.
Do I need a special CPU to run a hypervisor?
You need a CPU with hardware virtualization, which means Intel VT-x or AMD-V. Most CPUs made in the last decade have it. You may need to turn it on in the BIOS or UEFI settings.
Is VirtualBox a hypervisor?
Yes. VirtualBox is a type 2 hypervisor from Oracle. It runs on Windows, macOS and Linux hosts. It is a good free way to learn, but it is not built to host always-on services.
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