An operating system and application packaged together as a pre-installed system image for a virtualized environment such as VMware or Xen. A virtual appliance is the software appliance equivalent of a fixed-function hardware device (see hardware appliance). 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 the application. The processes are time consuming and configuration mistakes can be made. In contrast, virtual appliance deployment is faster because the appliance image (OS and application) is copied to the virtual machine pre-installed and pre-configured. The OS and application have already been tested together, and running the software is less error prone. See virtual machine, virtualization, software appliance, NFV and system image.