Root Partition - sometimes called partition. Manages machine-level functions such as device drivers, power management, and device host addition/removal. The root partition (or parent) partitions is the only partition that has direct access to physical memory and devices.
Child Partition - Partition that hosts a guest operating system, all access to physical memory and devices by a child partition is provided via the Virtual Machine Bus (VMBus) or the hypervisor.
A root partition creates child partitions using the hypercall application programming interface (API).
Input Output Memory Management Unit (IOMMU) is used to remap physical memory addresses to the addresses that used by the child partitions.
The parent partition hosts Virtualization Service Providers (VSPs) which communication over the VMBus to handle device access requests from child partitions. Child partitions host Virtualization Service Consumers (VSCs) which redirect device request to VSPs in the parent partition via VMBus.
Hypervisor - A layer of software that sits between the hardware and one or more operating systems. Its primary job is to provide isolated execution environments called partitions. The hypervisor controls and arbitrates access to the underlying hardware.
VMBus - Channel-based communication mechanism used for inter-partition communication and device enumeration on systems with multiple active virtualized partitions.
WMI - The VM Management Service exposes a set of Windows Management Instrumentation (WMI)-based APIs for managing and controlling virtual machines.