VM (Virtual Machine)
A VM (Virtual Machine) is a software-based emulation of a physical computer that runs its own operating system and applications on shared hardware.
What is a virtual machine (VM)?
A Virtual Machine (VM) is an isolated computing environment that behaves like a physical computer. It includes a virtual CPU, memory, storage, and network interfaces, and runs a full operating system (guest OS) on top of a hypervisor. Multiple VMs can run simultaneously on a single physical host, each independent from the others.
Why VMs matter
Virtual machines are fundamental to modern IT because they:
- Enable server consolidation and cost reduction
- Provide strong isolation between workloads
- Support rapid provisioning and scalability
- Simplify backup, snapshotting, and recovery
- Form the backbone of cloud and data center infrastructure
VMs are widely used in enterprises, cloud platforms, and development environments.
How VMs work
At a high level:
- A hypervisor abstracts physical hardware
- Virtual hardware is allocated to each VM
- Each VM runs its own operating system
- The hypervisor schedules and isolates resources
This allows different operating systems and workloads to coexist on the same host.
VM vs physical server
| Aspect | Virtual Machine | Physical Server |
|---|---|---|
| Hardware | Virtualized | Dedicated |
| Scalability | High | Limited |
| Isolation | Logical | Physical |
| Provisioning | Fast | Slow |
| Utilization | Optimized | Often underused |
VM vs container
- VM: includes a full operating system per instance; stronger isolation
- Container: shares the host OS kernel; lighter and faster
Both are commonly used together in modern architectures.
VMs in cloud computing
In cloud environments, VMs are the core unit of IaaS:
- On-demand provisioning
- Elastic scaling
- Global availability
- Pay-as-you-go pricing
Most cloud workloads ultimately run inside VMs, even when abstracted by higher-level services.
VM security considerations
From a security perspective:
- VM isolation limits blast radius
- Guest OS patching remains the customer's responsibility
- Hypervisor compromise can affect all VMs
- Snapshots and images must be protected
VM security relies on both platform hardening and guest OS controls.
Common VM use cases
Virtual machines are commonly used for:
- Hosting enterprise applications
- Running legacy operating systems
- Development and testing environments
- Disaster recovery and high availability
- Private, public, and hybrid cloud deployments
Common misconceptions
- "VMs are always slower than physical servers"
- "Containers fully replace VMs"
- "VMs don't need patching"
- "Cloud VMs are secure by default"