Twisted-Pair Cable
A twisted pair consists of two conductors (normally copper), each with its own plastic insulation, twisted together. One of the wires is used to carry signals to the receiver, and the other is used only as a ground reference.
Unshielded Versus Shielded Twisted-Pair Cable
The most common twisted-pair cable used in communications is referred to as unshielded twisted-pair (UTP). STP cable has a metal foil or braided mesh covering that encases each pair of insulated conductors. Although metal casing improves the quality of cable by preventing the penetration of noise or crosstalk, it is bulkier and more expensive.
The most common UTP connector is RJ45 (RJ stands for registered jack)
Applications
Twisted-pair cables are used in telephone lines to provide voice and data channels.
Local-area networks, such as l0Base-T and l00Base-T, also use twisted-pair cables.