Virtual machines, which were almost forgotten in the 1990s, have re-emerged as a method to install and consolidate many server systems into one physical machine. Many virtual machines can run on one host. Fast networks and CPUs now enable PCs to be hosted as virtual machines in central servers accessed from thin clients, just like the old time-sharing terminals, which improves the manageability of desktop computing. Complex, multi-tiered systems can be tested and deployed using virtual machines, which helps bring a wide array of configurations to the fingertips of developers, with no need to configure them by hand. Virtual machines present a common platform that simplifies software distribution for software developers--this helps tame the headaches of software installation and returns us to the simplicity of the "good old days" when there were few target platforms to worry about. Finally, the rise of Web-based systems has led to another reason to move back to the datacenter: cloud computing. Virtual machines offer a great solution for treating an entire cluster of servers as a single shared resource, sliced and diced according to the computing needs of the moment, not unlike the central mainframes of the past. This booklet gives you a starting point for understanding the VMware Infrastructure and deploying it for cost reduction, quicker deployments of systems, and better control of resource utilization, as well as datacenter management and high availability. Welcome to VMware Infrastructure.