VMware vApps is perhaps one of the most underutilized features of vCenter Server. A vApp is an application container, such as a resource pool.
You can assign multiple VMs to a vApp and then treat this set of VMs as a single application. You can configure the startup and shutdown order of the VMs or monitor the utilization and health of the vApp itself, instead of individual VMs.
Let's imagine a situation—you have a two-tier application, consisting of two database servers and one web frontend server. Those VMs are used only for this e-commerce application, so you can create a vApp and move VMs inside the vApp. On the vApp level, you can configure the resource parameter in terms of reservations, limits, and shares for the whole vApp, ...