Virtualisation
Running a 'virtual' system inside a real one
Virtual machines are complete, fully functional operating systems running inside some form of emulator. They can be used for a variety of purposes but are particularly useful for malware research where they act as complex sandboxes within which malware can be run safely and its behaviour analysed.
Virtual versions of Windows can be run on Linux platforms and vice versa; some systems even allow emulation of different hardware platforms. Virtualisation systems capable of running various full 'guest' operating systems to be run within a 'host' include VMware and Qemu.
