A hypervisor is software that sits between your computer's hardware and the operating systems running on it. It creates isolated virtual environments called virtual machines (VMs), each of which behaves like a separate, independent computer, even though they all share the same physical hardware underneath.
There are two main types. Type 1 hypervisors (bare-metal) run directly on the hardware without needing a host operating system; they are common in data centres and professional server environments. Type 2 hypervisors run inside an existing operating system (like Windows or macOS) and are used by individuals and organisations for testing, development, or running software that your main OS doesn't support.
For example, you might use a Type 2 hypervisor like VirtualBox or Parallels Desktop to run a Linux virtual machine on your Mac, without replacing macOS or rebooting. The hypervisor allocates processor cores, memory, and storage to each VM, and keeps them completely separate so that a crash in one VM doesn't affect the others.
When choosing hypervisor software, consider how many VMs you need to run at once, how much RAM and storage your computer has, and whether you need professional support or advanced features like live migration. Hypervisors are essential for developers testing code across different operating systems, IT professionals managing servers, and anyone who wants to run legacy or specialist software without buying extra hardware.