With vSphere vApp, you can package multiple interoperating virtual machines and software applications into a single unit that you can manage and distribute in OVF format.
A vApp can contain one or more virtual machines. Any operation carried out with the vApp, such as clone or power off, affects all virtual machines in the vApp container.
In the vSphere Web Client and the vSphere Client, you can navigate to the vApp Summary tab, where you can view the current status of the vApp, and you can manage the vApp.
Because the vApp metadata resides in the vCenter Server database, a vApp can be distributed across multiple ESXi hosts. The metadata information might be lost if the vCenter Server database is cleared or if the standalone ESXi host that contains the vApp is removed from the vCenter Server. Back up your vApps to an OVF package to avoid losing metadata.
vApp metadata for the virtual machines within the vApp does not follow the snapshot semantics for virtual machine configuration. The vApp properties that you delete, modify, or define after you take a snapshot of a virtual machine remain respectively deleted, modified, or defined, if the virtual machine reverts to that snapshot or any prior snapshots.