vCenter Server provides centralized management of hosts by allowing the vSphere Client to connect to vCenter Server instead of to individual hosts. In addition, vCenter Server is necessary if you want to use many of the advanced features in vSphere, such as VMotion, High Availability (HA), and the Distributed Resource Scheduler (DRS). Because of its centralized management capability, vCenter Server is a must-have in large environments where you have many hosts. vCenter Server is not included with vSphere and must be purchased separately. VMware does offer some bundles aimed at the small-business market, which makes vCenter Server more affordable by including it in a package with some host licenses.