Virtualization is a combination of software and hardware engineering that creates Virtual Machines (VMs) – an abstraction of the computer hardware that allows a single machine to act as if it where many machines.
Well known examples of Virtualisation
Most of the points mentioned in the section
Why are good enough to show when to use virtualization.
This needs technical understanding and expertise.
An important software which allows Physical machines to share their resources among virtual machines
There was a time when each citizen(the OS) of the city(the Datacenter) was roaming around and doing his business in his own car (the physical server). Most of the cars were some big SUVs with big engines, consuming too much and offering too much space and power than what one person would need. One day, some smart guys (IBM) decided it will be much more efficient to put all those citizens in a bus(host physical server) driven by an experienced driver(the hypervisor); there they can share the power of the big engine, the storage space and they can talk to each other faster.