Virtualization

In computing virtualization means lot.Simply it is the method of showing single physical resource(processor,storage devices) as multiple resources or vice versa.Nowadays virtual machines are getting very famous, because lot of computing problems can be solve using virtual machines.One well known virtual machine is Xen which is open source one.
The platforms that allows multiple operating systems to run on one machine is called Virtual Machine Monitor(VMM) or Hypervisor.

There are two types of hypervisors.

Type 1 hypervisor - Software that runs directly on hardware.So the guest OS run as 2nd level above hardware. E:g - Xen,Vmware's ESX server

Type 2 hypervisor - Software that runs within host's OS.So the guest OS runs as 3rd level of hardware. E:g - swsoft,VMware server

There are number of advantages of virtualization. It is very good method to resource sharing.There are lot of applications built with the help of virtualization.One such example is intruder detection systems(IDS).