Virtual Appliances Leadership Summit
Virtual Appliances

The growing acceptance of virtualization technology has opened the door to a new way of delivering applications using virtual appliances. A virtual appliance is an application combined with just enough operating system (JeOS) for it to run optimally in a virtual environment. Virtual appliances allow efficient deployment and maintenance of server-based applications.

Virtual appliances represent an unprecedented opportunity to streamline and simplify software distribution. With a virtual appliance, software vendors can ship thoroughly tested, standard configurations that require minimal installation effort. End-users are spared the complications of installing multiple supporting systems, since everything is contained in the virtual appliance package — the operating system, services and applications. This dramatically decreases potential support issues related to incorrectly configured software or hardware. Users can simply download a virtual appliance and run it on a hypervisor by vendors such VMware or Citrix, for example.

Read the definition on Wikipedia