Introduction
The IEEE 802.3af is more commonly known as Power over Ethernet. This standard states that power may be delivered by an end-point power source, using either the active data wires of an Ethernet port or the spare wires, to a powered device. It was originally intended to support power to IP phones however, rapid development of Power over Ethernet capable devices has extended its usage to other relevant applications such as wireless access points, Video surveillance cameras, digital signage and electronic badge readers.
For more information also visit What is Power over Ethernet (PoE)?
References
Power over Ethernet Solutions