The Xen Project is one of the leading open source virtualisation platforms. The Xen hypervisor is licensed under GPLv2. Like many of its competitors, Xen is also available in a commercial form from Citrix. Oracle VM is another commercial implementation of Xen. The Xen Project platform supports many cloud platforms such as Openstack, Cloudstack, etc. The Xen hypervisor provides an efficient and secure feature set for virtualisation of X86, IA64, ARM and other CPU architectures, and has been used to virtualise a wide range of guest operating systems, including Windows, Linux, Solaris and various versions of the BSD operating systems.