If you are deploying Horizon on vSphere, vCenter Server acts as a central administrator for VMware ESXi servers that are connected on a network. vCenter Server provides the central point for configuring, provisioning, and managing virtual machines in the data center.
In addition to using these virtual machines as sources for virtual machine desktop pools, you can use virtual machines to host the server components of VMware Horizon, including Horizon Connection Server instances, Active Directory servers, Microsoft RDS hosts, and vCenter Server instances.