A virtual machine image that includes the operating system and the application. It is packaged as a pre-installed system image for the particular virtualized environment and hardware platform it is targeted at; for example, VMware, Parallels or Xen virtual machines running on x86 computers.

Faster and Simpler
The regular process of deploying a new application in a virtualized computer is to set up a new virtual machine partition, install the operating system and then install the application. The installation processes are time consuming and configuration mistakes can be made. In contrast, virtual appliance deployment is faster. The appliance image (OS and application) is copied to the virtual machine pre-installed and pre-configured. There is no tedious installation, and since the OS and application have already been tested together, the operation of the programs is less error prone. See virtual machine, virtualization, software appliance and system image.