The most commonly used form of twisted pair is unshielded twisted pair (UTP). It is just two insulated wires twisted together. Any data communication cables and normal telephone cables are this type. Shielded twisted pair (STP) differs from UTP in that it has a foil jacket that helps prevent crosstalk and noise from outside source. In data communications there is a cable type called FTP (foil-shielded pairs) which consists of four twisted pair inside one common shield (made of aluminum foil).