Virtualization means creating virtual form of hardware and/or software resources. Virtualization of server means partitioning physical server into several virtual servers, or machines. In which each virtual machines are isolated, so it can interact with other devices, applications, user and data independently. So it helps to install/run different operating systems in virtual machines although it runs under same physical server. Since it has the isolation feature, if one virtual machine crashes it will not affect the another virtual machine.
Virtualization is not only about partitioning resources, it can also combine group of physical server into single server. Main concept of virtualization is utilizing the resource usefully by either partitioning or combining.
Why virtualization?
Take an example of data center, most of the machines utilize only 10-15% of its total capacity most of the time which results in wastage of electricity and maintenance cost.To make the optimal utilisation of the remaining capacities we can use Virtualization concepts which also helps to avoid installation of platform/application specific data centers.
