Virtualization is the creation of a virtual version of a server, desktop, storage device, operating system or network resource. In other words, virtualization is a technique, which allows sharing a single physical instance of a resource or an application among multiple customers and organizations. There are different types of virtualization:

Hardware Virtualization: Creation of a virtual machine over existing operating system and hardware is known as hardware virtualization. A virtual machine provides an environment that is logically separated from the underlying hardware.

The installation of the virtual machine software or virtual machine manager directly on the hardware system is known as hardware virtualization. After the virtualization of hardware system one can install different operating system on it and run different applications on those operating systems. Hardware virtualization is mainly done for the server platforms, because controlling virtual machines is much easier than controlling a physical server.

Operating System Virtualization: Installation of the virtual machine software or virtual machine manager on the host operating system instead of directly on the hardware system is known as operating system virtualization. Operating system virtualization is mainly used for testing the applications on different platforms of operating systems.

Server Virtualization: Installation of the virtual machine software or virtual machine manager on the Server system is known as server virtualization. Server virtualization is used for when a single physical server needs to be divided into multiple servers for balancing the load.

Storage Virtualization: Storage virtualization is the process of grouping the physical storage from multiple network storage devices. Storage virtualization is also implemented by using software applications. Storage virtualization is mainly done for backup and recovery purposes.