Category 6 cable, commonly referred to as Cat 6, is a standardized cable for Gigabit Ethernet and other network physical layers that is backward compatible with the Category 5/5e and Category 3 cable standards.

Compared with Cat 5 and Cat 5e, Cat 6 features more stringent specifications for crosstalk and system noise. The cable standard provides performance of up to 250 MHz and is suitable for 10BASE-T, 100BASE-TX (Fast Ethernet), 1000BASE-T/1000BASE-TX (Gigabit Ethernet) and 10GBASE-T (10-Gigabit Ethernet).

Category 6 cable has a reduced maximum length when used for 10GBASE-T, however Category 6a cable, (or Augmented Category 6), is characterized to 500 MHz and has improved alien crosstalk characteristics, allowing 10GBASE-T to be run for the same distance as previous protocols.

Category 6 and Category 6a cable can be identified by the printing on the side of the cable sheath.

Cat 6 patch cables are normally terminated in 8P8C modular connectors. If Cat 6 rated patch cables, jacks and connectors are not used with Cat 6 wiring, overall performance is degraded and will not meet Cat 6 performance specifications.

Connectors use either T568A or T568B pin assignments; although performance is comparable provided both ends of a cable are the same.