ZigBee is included here due to the large amount of press available on the protocol. At time of publishing, the vast majority of ZigBee products and applications exist only in the commercial and/or utility industries. Few consumer products exist.
ZigBee is a protocol for communication among devices used for home automation. It uses RF for signaling and control. ZigBee is made to operate on IEEE 802.15.4 radios. It should be made clear that the 802.15.4 radio is a hardware layer, which numerous and incompatible protocol stacks can function on. Therefore, many products which are based on 802.15.4 may are not compatible.
ZigBee was originally developed by the HomeRF Alliance and is now managed by the Zigbee Alliance. Development began in 1997, yet over the 15+ years of protocol, standards and specifications work, very few products exist in the home automation space. The first standard was published in 2003 only to become obsolete upon the superseding 802.15.4-2006 in 2006.
While the ZigBee Alliance has produced a large amount of PR and has many manufacturers building chips and development kits, few products have been released into the home automation space. ZigBee products are much more expensive than their primary competition (INSTEON and Zwave).
Interoperability remains a major concern with ZigBee labeled products. Widespread reports of incompatibilities between brands exist.
While the ZigBee standard is open for non-commercial use (hobbyists), the commercial requirements for membership in the ZigBee Alliance causes problems for open-source developers because the annual fee conflicts with the GNU General Public Licence. The requirement for the developer to join the ZigBee Alliance similarly conflicts with most other free software licenses.