Back in 1999, when VMware first released its type-2 hypervisor, VMware Workstation, a new world opened up: Suddenly, you could run multiple operating systems on the same PC. But the real tipping point for virtualization was 2001, with the release of VMware ESX Server, a type-1 hypervisor that installed on bare metal, vastly improving hardware utilization. That kicked off what I call the decade of virtualization.
VMware wasn’t alone for long, although as first mover it always seemed to stay a step ahead. Citrix Xen and later Microsoft Hyper-V arrived, the latter gradually closing the gap on features and performance. VM management, migration/failover options, and so forth kept the war going. For those running Windows Server, there was an added attraction: Hyper-V was bundled at no extra cost.