It is a technology which allows partitioning of a single physical server into no of small servers with the help of visualization software.Virtualization enables single dedicated server to run several operating systems. So you can manage services separately, host more websites, and serve more users, all more cost-effectively.It is a good solution for small to medium scale application. It has been a proven technology for more than a decade but still many in the industry unawre of this facility, thus spending much on buying multiple physical servers.

Key Benefits :
Easy Migration :one of the more powerful features of server virtualization is the ability to move a running virtual machine from one host to another with almost zero downtime.
Cost Saving : Not only will your company save on the physical server hardware, power and cooling of the servers that were consolidated, you’ll also save on the time it used to take to administer physical servers. With a lagging economy, IT departments and server admins are bound to achieve more with less. Server virtualization makes IT admins more efficient and agile, allowing the users to do more with less resource
Less Downtime : Virtualized servers being up and running so much more than those same servers that were running directly on physical hardware, the downtime is very less.
Image-based backup and restore : By being able to back up and restore entire virtual machines, you can much more quickly back up the VMs and put them back, if needed. Additionally, image-level backups make disaster recovery so much easier
Simplified disaster recovery : Virtual machines being hardware-independent (not tied to a particular physical server) you can restore image-based backups on any hardware in the event of disaster .Snapshot mechanism comes handy in virtual machine data restoration