Power over Ethernet or PoE describes any of several standardized or ad-hoc systems which pass electric power along with data on twisted pair Ethernet cabling. This allows a single cable to provide both data connection and electric power to devices such as wireless access points and IP cameras. There are several common techniques for transmitting power over Ethernet cabling. Two of them have been standardized by IEEE 802.3 since 2003. Only two of the total four twisted pairs in an Ethernet cable are used for data in 10BASE-T or 100BASE-TX Ethernet; thus, power can be transmitted on the unused two pairs.