Power over Ethernet or PoE technology describes a system to safely pass electrical power, along with data, on Ethernet cabling. Power can come from a power supply within a PoE-enabled networking device such as an Ethernet switch or from a device built for "injecting" power onto the Ethernet cabling, dubbed Midspan.

Uses for PoE include:

Powering VoIP phones
Powering networking equipment such as routers and wireless access points
Powering devices such as network webcams