The process of creating a virtual version of something such as an operating system, a server, storage devices, or network resources. Operating system virtualisation enables the user to use a software to run multiple operating systems on the same computer hardware. Some virtualisation software also allows you the capability of dynamically adding more hardware to increase the power and range of the virtualised software. There are three main areas of virtualisation that are increasingly becoming popular. One is network virtualisation, where the combined bandwidth of the network is split into several channels independent from each other and which can be assigned to a particular server or device in real time. By using virtualisation, users need not be concerned with the underlying complexity of the actual physical network. The second is to consolidate storage from multiple network storage devices into a single virtualised storage device that is managed from a single place. As far as the end-user is concerned, he will be dealing only with a hard disk, and will have no idea whether the drive is virtualised or not. The third is in server virtualisation, where a user may have full access to a range of operating system services in a virtualised environment.