Power over Ethernet (PoE) is a networking feature defined by the IEEE 802.3af and 802.3at standards. PoE lets Ethernet cables supply power to network devices over the existing data connection. PoE-capable devices can be power sourcing equipment (PSE), powered devices (PDs), or sometimes both. The device that transmits power is a PSE, while the device that is powered is a PD. Most PSEs are either network switches or PoE injectors intended for use with non-PoE switches. Common examples of PDs include VoIP phones, wireless access points, and IP cameras.