The document provides an overview of the Zigbee protocol. It describes the Zigbee stack architecture and device types. It explains address allocation and various examples of cluster tree and mesh routing topologies. It also discusses the Zigbee Alliance standards organization and the Zigbee certification process. The history and features of the Zigbee and Zigbee Pro specifications are outlined. Finally, it summarizes several Zigbee application profiles including smart energy, home automation, commercial building automation, and personal health care.