VMware vCenter Server provides centralized management for datacenters.

vCenter Server aggregates physical resources from multiple ESXi hosts and presents a central collection of flexible resources for the system administrator to provision to virtual machines in the virtual environment.

vCenter Server components are user access control, core services, distributed services, plug-ins, and various interfaces.

vCenter Server Components
This image shows the key components of vCenter Server.

The User Access Control component allows the system administrator to create and manage different levels of access to vCenter Server for different classes of users.

For example, a user class might manage and configure the physical virtualization server hardware in the datacenter. Another user class might manage virtual resources within a particular resource pool in the virtual machine cluster.