To start the journey, one needs a foundation to start. I assume everyone knows what a hypervisor is, but if you don’t check out Wikipedia.
VMware has been the leader for a number of years, along with another vendor and open source, like Xen and KVM. Microsoft also has a hand in Virtualization early on in the with Virtual Server, which was originally developed by Connectix, but no real traction and frankly it sucked..