VMware vSphere Hypervisor is based on VMware ESXi, the hypervisor architecture that sets the industry standard for reliability, performance and ecosystem support. VMware vSphere Hypervisor is the easiest way to get started with virtualization—and it’s free. Consolidate your applications onto fewer servers and start saving money through reduced hardware, power, cooling and administration costs. With VMware vSphere Hypervisor, you can:
- Run multiple applications on a single server
- Run a greener datacenter and reduce energy costs
- Back up and recover applications more easily
- Virtualize even business-critical applications
http://www.vmware.com/products/vsphere-hypervisor/overview.html