Virtual machine (VM)
A virtual machine (VM) is an isolated computing environment that emulates a computer on shared physical hardware.
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Definition
A virtual machine (VM) is an isolated computing environment that emulates a computer on shared physical hardware.
How it works
A hypervisor carves one physical machine into several virtual ones, each with virtual CPUs, memory, disks, and network interfaces, and each booting its own operating system. The guests cannot see each other — which is exactly what makes it safe to run separate customers, or separate environments, on shared hardware.
Example: A hosting provider can run several independent Linux virtual machines on one physical server.
Often confused: A VM carries a full guest operating system; a container shares the host's kernel and packages just the application.
Related terms
Sources
- NIST SP 800-125: Security for Full Virtualization Technologies
- NIST Computer Security Resource Center Glossary
Last reviewed 2026-07-19.