Zigbee networks are called personal area networks (PANs). Each network is defined with a unique PAN identifier (PAN ID), which is common among all devices of the same network. Zigbee devices are either preconfigured with a PAN ID to join, or they can discover nearby networks and select a PAN ID to join.
Zigbee supports both a 64-bit and a 16-bit PAN ID. Both PAN IDs are used to uniquely identify a network. Devices on the same Zigbee network must share the same 64-bit and 16-bit PAN IDs. If multiple Zigbee networks are operating within range of each other, each should have unique PAN IDs.