Twisted Pair - Pair of copper wires that run together at six twists per inch; may be shielded (STP) or unshielded (UTP).  Together, the two wires carry an electrical signal between devices. The data rate supported by transmission over twisted pair wiring is limited to a 100 Mbps or so over short distances and several Mbps over distances on the order of 10,000 feet, and to 1 Mbps or less over much longer distances. The twisting provides a measure of protection from electromagnetic and radio-frequency interference.