Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electrical power along with data on Ethernet cabling. This allows a single cable to provide both data connection and electrical power to devices such as wireless access points or IP cameras. Unlike standards such as Universal Serial Bus which also power devices over the data cables, PoE allows long cable lengths. Power may be carried on the same conductors as the data, or it may be carried on dedicated conductors in the same cable.
The Internet is becoming as essential and ubiquitous a tool for communication and entertainment as are television and the telephone. An ever-growing variety of powered devices (PDs) such as wireless routers, web cameras, VoIP phones, and others are finding more and more applications in facilitating and extending the usefulness of the Internet. All of these devices require a power source to run them and, although the obvious source of this power is the mains, this choice is unattractive because of the additional cables that need to be introduced. A far better solution is to use the Ethernet cable that transfers data to also carry power from the Ethernet hub to the PD, thus eliminating extra cables.