Virtualisation provides a layer of abstraction that hides the physical computing resource from an application or end user. It masks complexity and enables much more efficient utilisation of resources. Virtualisation extends to servers, storage and desktops.

 Some of the most signifcant benefits of virtualisation include:

• Better usage of server capacity. Typical server usage rates can be as low as 5 or 10%. Virtualisation enables managed usage of spare server capacity, reducing systems costs.
• Better usage of storage capacity. Pooling storage can help administrators improve upon the typical 40% to 50% capacity utilisation rates. And where you're mirroring to a secondary site, this can represent significant benefit.
• Saving physical space and energy consumption. Higher utilisation rates equates to fewer servers, in turn reducing physical footprint, power and cooling requirements.
• Ability to deploy a new system without ordering new hardware saving installation, build and testing time.
• Quicker backups. By taking a data snapshot, virtualisation software can eliminate the bottleneck between the application server and backup server.
• Automated management. Automation can include automatic capacity addition if a database is running out of space.
• Application testing. Instead of testing an application against actual production data, you can use virtualisation to create a replicated data set to safely test an application against.
• Application & database performance.Critcal files can be assigned to very high speed storage devices without affecting the
  function of theapplication.
• High availability. By separating storage from the application, virtualisation insulates an application from a server failure.
• Resource sharing between heterogeneous servers. A virtualisation engine can ensure that servers running different operating systems can safely coexist.