Introduction to Virtualization (viadmin.com)
To help you understand how VMware Virtual Infrastructure works, lets first provide some background on VMwares virtualization technology. I am going to compare what are the differences between a traditional hardware server and a virtual server? The so called Virtualization layer is represented by ESX Server which installs on a bare metal and separates operating system and applications from hardware and firmware by presenting a virtualized CPU, memory, hard drives and network cards to the Operating System. ESX Server consists of two main components that implement the virtual platform: the Virtual Machine Monitor and the VMKernel. A Guest operating system (virtual machine) such as Windows or Linux runs on top of this virtual platform. The server administrator uses ESX management console called VMware Infrastructure Client to manage and divide one physical server into multiple isolated virtual environments called virtual machines.