@nikade It's because it's often a misnomer. There reason is simple: Dom0 is indeed the place where you SSH, having an almost regular Linux system (at first sight), the toolstack, backup export etc. So it seems indeed to be "the host".
However, in "reality", the host is the entire resources of the machine, all CPUs and memory. It includes the Dom0, but not only (Dom0 doesn't have access to all CPU and memory, "only" all physical devices): all other VMs.
The difference is subtle enough, especially for people not coming from Xen, "Dom0" doesn't give any clue about what it is ("Control Domain" is a bit better, even if "Domain" is still less clear than "Virtual Machine"). That's because when you boot, you do NOT boot Linux but a micro-kernel, Xen, that does have access to all the host. That's also what makes Xen design more secure than others: only a small kernel (200k LoC) has access to everything, unlike in KVM for example, where it's the full kernel with at least 20M LoC. But you cannot access "Xen" with SSH or anything, outside sending commands from the Dom0. Hence the confusion.
That's why I'm even myself, on regular basis, uses "host" instead of Dom0 in the sake of simplicity/clarity.
