A PoE camera draws power and sends video over a single Ethernet cable, removing the need for separate wiring at the mounting point. Power negotiation happens between the camera and a PoE switch or injector before the port energizes. IEEE 802.3af suits most camera boards, while 802.3at/bt fit devices with heaters, motors, or PTZ heads. Cable runs max out at 100m per the Ethernet standard, extendable via fiber or extenders.