FTP (foil screened twisted pair) cable is a cable containing multiple pairs of copper wire enclosed in a sheath of aluminum foil. It's used in wiring systems in buildings or other environments where heavy noise adjacent to the wire might cause interference. The foil provides insulation not afforded by UTP (unshielded twisted pair), the most common kind of structural wiring. The disadvantage of FTP is that it requires somewhat more care in "earthing" (grounding) than UTP and electrical impedances must be matched when connecting to UTP. Typically, FTP might be used in a factory setting and UTP in an office setting.