Xen, KVM, and other Linux-based hypervisors support a single generic API called libvirt. For most tasks, it doesn’t matter which Linux hypervisor you are using. You can use the same basic tools. libvirt has its own terminology which will be helpful to know when reading the libvirt section.
A node is a single physical machine.
A hypervisor is a layer of software that virtualizes a node, providing a set of virtual machines that may differ from the node itself.
A domain is an instance of an operating system running on a virtualized machine provided by the hypervisor.
Throughout this chapter, though, we’ll stick to more common industry terminology, referring to a domain as a guest and the node running the guest as a host.