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 performance.
When used as a virtualizer, QEMU achieves near native performances by executing the guest code directly on the host CPU. QEMU supports virtualization when executing under the Xen hypervisor or using the KVM kernel module in Linux. When using KVM, QEMU can virtualize x86, server and embedded PowerPC, and S390 guests.
In Windows :
you can install qemu from scratch and configure it manually but there is already a nice tool for windows called MobaliveCD download that it don’t required installation just download and open it as administrator .
choose disk and click create .
Open MobaLiveCD as administrator
In Mac :
Install qemu using homebrew
brew update brew install qemu
for testing USB
sudo qemu-system-x86_64 -m 1024 -usb /dev/rdisk2
where rdisk2 is your USB drive location & for testing ISO
sudo qemu-system-x86_64 -m 1024 linuxmint-16-cinnamon-dvd-64bit.iso
In Linux :
you can install qemu in debian and ubuntu based system using apt-get install in other distribution just use your default package manager and search for qemu .
sudo apt-get install qemu-system
Now open terminal
and now you can use processor virtualization and test your ISO and USB drives .
qemu-system-x86_64 -m 512 linuxmint-16-cinnamon-dvd-64bit.iso