KVM virtualisation
The Kernel Virtual Machine is a hypervisor for Linux on hardware with virtualization extensions (Intel VT or AMD-V). It is deployed as a loadable kernel modules, kvm.ko, and either kvm-intel.ko or kvm-amd.ko.
The KVM Debian Wiki rocks, and provides details on the basics including a great performance tuning section.
Install Administration tasks User specific vs system wide VMs List VMs Start VM Shutdown VM Murder (hung) VM Autostart default NATed bridged network What if the default network interface is not listed How to extend / increase a partition Use network ISO source for new VMs Windows VM disk driver Install Easy instructions to get QEMU/KVM and virt-manager up and running on Arch.