Vrtual machines environment is one of the most commonyl used techology in the IT.
Since 2007 Ada consulting used virtualization as a primary resorce for operating systems installatons, with the following advantages:

• high scalability: changing the customers' needs for performances and hardware resources is not a problem using virtualization techologies, because virtual hardware is easly upgradable, even if the hypervisor itself is upgraded.
• high availblity: high-end hypervisors can act an active-passive or active-active host cluster, making application services available even in a hotst-degraded environment
• test environment: every application service can be tested against software bugs, hardware compliance, interoperability and load tests, without interference with the productional environmet, because VMs can be deployed to test the software behaviour before putting them in prodution-stage.
• application service isolation: every software application can be run on an isolated envronment, to grant the maximum reliability; VMs resources can be easly tailored and/or restricted to those really needed, to avoid computational reources overcommitment.

There are several Virtual Machines technologies, depending on virtualizaton types (full or hybrid), Virtual Machines resources sharing tecniques, storage types and network virtualization.
The high-end technologies can easly manage more than one datacentre at the same time and even allow network users to access their Virtual Desktop (VDI) from a thinclient machine.