Explain the concept of a virtual machine and its main functions.

A virtual machine (VM) is a software or hardware environment that emulates the operation of a physical computer. It allows running operating systems and applications in an isolated and controlled environment.

Main functions of a virtual machine:

• Isolation: VM isolates the guest OS and applications from the host and other VMs, enhancing security and stability.
• Hardware abstraction: VM provides virtualized resources (processor, memory, disks), hiding the details of physical hardware.
• Resource management: Allows distributing and limiting resources among different VMs.
• Migration and snapshots: Enables saving the state and moving VMs between physical servers without interruption.

Example: on a single physical server, using a hypervisor, you can run multiple VMs with different OSes for testing or service isolation.