Category 5 cable, commonly known as Cat 5, is an unshielded twisted pair cable type designed for high signal integrity. With the 2001 introduction of the TIA/EIA-568-B standard, the category 5 cabling specification was made obsolete and superseded by the category 5e specification.

Category 5 cable included four twisted pairs in a single cable jacket. Cat 5 cable typically had three twists per inch of each twisted pair of 24 gauge copper wires within the cable. Cat 5 cables were often used in structured cabling for computer networks such as Fast Ethernet, although they were also used to carry many other signals such as basic voice services, token ring, and ATMs.

Cat 5e cable is an enhanced version of Cat 5 that adds specifications for far-end crosstalk. Although 1000BASE-T was designed for use with Cat 5 cable, the tighter specifications associated with Cat 5e cable and connectors make it an excellent choice for use with 1000BASE-T. Despite the stricter performance specifications, Cat 5e cable does not enable longer cable distances for Ethernet networks: horizontal cables are still limited to a maximum of 90 m in length.