A twisted pair cable is a widely used cable for transmitting data and information over certain distances. Two common types of twisted pairs are – unshielded twisted pair and shielded twisted pair.
Unshielded Twisted Pair (UTP)
UTP consists of color-coded copper wires but does not include any foil or braiding as an insulator to protect against interference. The cable has four pairs of wires inside the jacket. Each pair is twisted with a different number of twists per inch to help eliminate interference from adjacent pairs and other electrical devices.
UTP cables are suitable for offices and homes. They are less expensive than STP cables. So if the interference or crosstalk is not your main concern, it is suggested to choose UTP cable for saving your cabling cost.
Shielded Twisted Pair (STP)
STP contains an extra foil wrapping or copper braid jacket to help shield the cable signals from interference. The additional shielding in the STP cable stops electromagnetic interference from leaking out of or into the cable. STP cable is used to eliminate inductive and capacitive coupling. Twisting cancels out inductive coupling, while the shield eliminates capacitive coupling.
STP cables are often used in situations nearby equipment causing EMI (Electro-Magnetic Interference). For example, airports, medical centers and factories have lots of machines that can produce interference, in these places STP cables are typically applied.