virtual machine

A computer within a computer, implemented in software. A virtual machine emulates a complete hardware system, from processor to network card, in a self-contained, isolated software environment, enabling the simultaneous operation of otherwise incompatible operating systems. Each operating system runs in its own isolated software partition.

a partitioned, isolated, and encapsulated abstraction of physical hardware to present a consistent, logical image of hardware resources (processor, memory, disk, network) to a hosted operating system to enable server virtualization.

An empty, isolated, virtual environment, lying on top of a host OS, equipped with virtual hardware (processor, memory, disks, network interfaces, etc.) and managed by a virtualization product. It's where the guest OS is installed.

A representation of a real machine using software that provides an operating environment which can run or host a guest operating system.

A virtualized x86 PC environment in which a guest operating system and associated application software can run. Multiple virtual machines can operate on the same host system concurrently.

The environment in which a hosted operating system runs, providing the abstraction of a dedicated machine. A virtual machine may be identical to the underlying hardware (as in full virtualisation, or it may differ, as in paravirtualisation.

See Java Virtual Machine (JVM).

An abstract specification for a computing device that can be implemented in different ways, in software or hardware. You compile to the instruction set of a virtual machine much like you'd compile to the instruction set of a microprocessor. The Java virtual machine consists of a bytecode instruction set, a set of registers, a stack, a garbage-collected heap, and an area for storing methods.