Black and Wiliam (1998a) also noted that for assessment to function formatively, the feedback information had to be used, and thus the differential treatments that are incorporated in response to the feedback are at the heart of effective learning.
A hypervisor is a unique type of software that allows a computer to run more than one operating system (OS). Through a process known as virtualization, the software tricks each OS into thinking it has exclusive access to a particular set of hardware.
This is when the hypervisors are run on the host's hardware to control it as well as manage the virtual machines on it. If you are currently using Microsoft Hyper-V hypervisor, VMware ESX/ESXi, Oracle VM Server for x86, KVM, or Citrix XenServer, then this is the type of hypervisor with which you are working.