is a generic and open source machine emulator and virtualizer for i386 CPUs.
QEMU is an emulator for various CPUs. It works on Linux, Windows, FreeBSD and Mac OS X.
QEMU is a generic and open source machine emulator and virtualizer.http://fabrice.bellard.free.fr/qemu/download.html
When used as a machine emulator, QEMU can run OSes and programs made for one machine (e.g. an ARM board) on a different machine (e.g. your own PC). By using dynamic translation, it achieves very good performances.
When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. A host driver called the QEMU accelerator (also known as KQEMU) is needed in this case. The virtualizer mode requires that both the host and guest machine use x86 compatible processors.