QEMU is a generic and open source machine emulator and virtualizer. 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.
QEMU Front End GUI
Currently there are two GUIs for QEMU
GTK+ front-end to QEMU computer emulator Qemu Launcher provides a graphical front-end to all basic, and many advanced QEMU computer emulator options. It allows you to create, save, and run multiple virtual machine configurations, create and convert disk images.