VMware ESX is an enterprise-level computer virtualization product offered by VMware, Inc. ESX is a component of VMware's larger offering, VMware Infrastructure, and adds management and reliability services to the core server product. The original ESX is being replaced by ESXi. VMware ESX and VMware ESXi are bare-metal embedded hypervisors that are VMware's enterprise software hypervisors for servers that run directly on server hardware without requiring an additional underlying operating system. The basic server requires some form of persistent storage (typically an array of hard disk drives) for storing the hypervisor and support files. A smaller footprint variant, ESXi, does away with the first requirement by permitting placement of the hypervisor onto a dedicated compact storage device. Both variants support the services offered by VMware Infrastructure. Remember : This is Proprietary.